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Peter Schumacher - One of the best experts on this subject based on the ideXlab platform.
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cluster formation at the Si liquid interface in sr and na modified al Si alloys
Scripta Materialia, 2016Co-Authors: Jenifer Barrirero, Michael Engstler, Peter Schumacher, Naureen Ghafoor, Magnus Oden, Frank MucklichAbstract:Abstract Atom probe tomography was used to compare Na and Sr modified Al–Si hypoEutectic alloys. Both Na and Sr promote the formation of nanometre-Sized clusters in the Si Eutectic phase. CompoSitional analyses of the clusters show an Al:Sr ratio of 2.92 ± 0.46 and an Al:Na ratio of 1.07 ± 0.23. It is proposed that SrAl 2 Si 2 and NaAlSi clusters are formed at the Si/liquid interface and take part in the modification process by altering the Eutectic Si growth.
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revealing heterogeneous nucleation of primary Si and Eutectic Si by alp in hyperEutectic al Si alloys
Scientific Reports, 2016Co-Authors: Fredrik S Hage, Xiangfa Liu, Quentin M Ramasse, Peter SchumacherAbstract:The heterogeneous nucleation of primary Si and Eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and Eutectic Si in hyperEutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hyperEutectic Al-Si alloys. P, in the form of AlP particles, was observed in the centre of primary Si. However, no Significant amount of P was detected within primary Si, Eutectic Si and the Al matrix. Instead, P was observed at the interface between the Al matrix and Eutectic Si, strongly indicating that P, in the form of AlP particles (or AlP ‘patch’ dependent on the P concentration), may have nucleated on the surface of the Al matrix and thereby enhanced the heterogeneous nucleation of Eutectic Si. The present investigation reveals some novel inSights into heterogeneous nucleation of primary Si and Eutectic Si by AlP in hyperEutectic Al-Si alloys and can be used to further develop heterogeneous nucleation mechanisms based on adsorption.
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nucleation and growth of Eutectic Si in al Si alloys with na addition
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2015Co-Authors: Jenifer Barrirero, Michael Engstler, Hisham Aboulfadl, F Mucklich, Peter SchumacherAbstract:Al-5 wt pct Si-based alloys with Na additions (19 and 160 ppm) have been produced by controlled sand casting and melt spinning. Entrained droplet technique and differential scanning calorimetry were employed to investigate the nucleation behavior of Eutectic Si. High-resolution transmisSion electron microscopy and atom probe tomography were used to investigate the distribution of Na atoms within Eutectic Si and at the interfaces between Eutectic Si and Eutectic Al. It was found that (i) only 19 ppm Na addition results into a high undercooling (49 K (49 °C)) of the entrained Eutectic droplet. However, further increaSing Na addition up to 160 ppm exerts no poSitive effect on the nucleation of Eutectic Si, instead a decreased undercooling (29 K (29 °C)) was observed. (ii) Na addition suppresses the growth of Eutectic Si due to the Na segregation at the interface between Eutectic Si and Eutectic Al, and (iii) Na addition promotes Significant multiple Si twins, which can be attributed to the proposed adsorption of Na atoms at the intersection of Si twins and along the 〈112〉Si growth direction of Si. The present investigation demonstrates, for the first time, a direct observation on the distribution of Na atoms within Eutectic Si and thereby provides strong experimental supports to the well-accepted impurity-induced twinning growth mechanism and poisoning of the twin plane re-entrant edge growth mechanism.
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modification of Eutectic Si in al Si alloys with eu addition
Acta Materialia, 2015Co-Authors: Xiangdong Wang, T H Ludwig, Yoshiki Tsunekawa, Lars Arnberg, Jianzhong Jiang, Peter SchumacherAbstract:Abstract Al–5 wt.% Si-based alloys with 0.05 wt.% Eu addition were produced by controlled sand-casting and melt-spinning, respectively. The modification of Eutectic Si caused by 0.05 wt.% Eu addition was investigated by thermal analySis, differential scanning calorimetry and multi-scale microstructure characterization techniques. In the case of controlled sand-casting, 0.05 wt.% Eu addition was found to modify the Eutectic Si into a fibrous morphology. Multiply twinned Si particles were observed within Eutectic Si. Furthermore, the Al 2 Si 2 Eu phase was also observed both in the vicinity of Eutectic Si and within Eutectic Si, which was believed to hinder Si growth. In the case of melt-spun samples, nanometer-Sized Al 2 Si 2 Eu phases were observed. However, after controlled cooling in a differential scanning calorimeter, multiply twinned Si particles were observed. The formation of multiply twinned Si particles was attributed to the adsorption of Eu atoms along the 〈1 1 2〉 Si growth direction of Si and at the intersection of two {1 1 1} Si facets. Twinning was observed in both fundamentally different casting processes: controlled sand-casting and melt-spinning. This is fully conSistent with the well-known poisoning of the twin plane re-entrant edge and the impurity-induced twinning modification mechanisms.
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solute adsorption and entrapment during Eutectic Si growth in a Si based alloys
Acta Materialia, 2015Co-Authors: Jiehua Li, Mihaela Albu, Ferdinand Hofer, Peter SchumacherAbstract:Abstract The solute adsorption and/or segregation as well as the solute entrapment of Sr, Na and Yb atoms during Eutectic Si growth in a series of high-purity Al–5 wt.% Si alloys was investigated by multi-scale microstructure characterization techniques, including high-resolution transmisSion electron microscopy and atomic-resolution scanning transmisSion electron microscopy. The adsorption of Sr atoms was directly observed along the 〈1 1 2〉Si growth direction of Si and/or at the intersection of multiple Si twins, which can be used to interpret the poisoning of the twin plane re-entrant edge and impurity induced twinning modification mechanisms, respectively. In contrast, Yb shows a different mechanism compared to the adsorption of Sr atoms. No Significant Yb-rich cluster was observed at the intersection of Si twins. However, conSiderable Yb-rich segregation lines were observed along the 〈1 1 2〉Si direction, which can be attributed to the solute entrapment caused by a few Si twins through the natural twin plane re-entrant edge and growth mechanism. Active poisoning of the twin plane re-entrant edge and impurity induced twinning growth mechanisms cannot be observed due to the absence of Yb atoms within Eutectic Si. Furthermore, the solute entrapment of modifying elements (X, Sr or Yb) together with Al and Si was proposed to interpret the formation of Al2Si2X phases or X-rich clusters within Eutectic Si. Such types of Al2Si2X phases or X-rich clusters were further proposed to be an “artefact” caused by the solute entrapment during Eutectic Si growth, rather than an active factor affecting the modification. The observed solute adsorption and entrapment can be used to interpret the different observations in the cases of different modifying elements, including impurity effects and so-called “quenching modification”, thereby elucidating the modification of Eutectic Si in Al–Si alloys.
Hongseok Choi - One of the best experts on this subject based on the ideXlab platform.
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al2o3 nanoparticles induced Simultaneous refinement and modification of primary and Eutectic Si particles in hyperEutectic al 20Si alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012Co-Authors: Hongseok Choi, Hiromi Konishi, Xiaochun LiAbstract:Abstract It is well known that the mechanical properties of hyperEutectic Al–Si alloys are affected by the Size, volume fraction, and distribution of primary and Eutectic Si particles. However, it is very difficult to Simultaneously refine and modify Si particles in hyperEutectic Al–Si alloys by conventional means. This study investigates an effect of nanoparticles on Si particles during solidification in hyperEutectic Al–Si alloys. Various contents of γ-Al 2 O 3 nanoparticles were added in hyperEutectic Al–20Si alloy melt and further dispersed through an ultrasonic cavitation based technique. The cast hyperEutectic Al–20Si alloy with the nanoparticle addition showed a Significant enhancement in both strengths and ductility. The ductility of the cast hyperEutectic Al–20Si alloy was increased from 0.37% to 1.72% with an addition of 0.5 wt% γ-Al 2 O 3 nanoparticles. Yield strength and ultimate tenSile strength of the nanocompoSite also showed an improvement of about 6% and 26%, respectively. Study suggests that γ-Al 2 O 3 nanoparticles effectively induced Simultaneous refinement of primary Si and modification of Eutectic Si, resulting in superior ductility enhancement that is much higher than that conventional methods can offer. Microstructural analySis with optical and scanning electron microscope (SEM) revealed that the primary Si particles were refined from large star shapes with small features to polygon or blocky shapes with smooth edges and corners. Moreover, the large plate Eutectic Si particles were also modified into the fine coralline-like ones. The results could have great potential for numerous applications.
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refinement of primary Si and modification of Eutectic Si for enhanced ductility of hyperEutectic al 20Si 4 5cu alloy with addition of al2o3 nanoparticles
Journal of Materials Science, 2012Co-Authors: Hongseok ChoiAbstract:It is very difficult to Simultaneously refine and modify Si particles in hyperEutectic Al–Si–Cu alloys to enhance their ductility. This study investigates how nanoparticles affect Si particles during solidification in hyperEutectic Al–Si–Cu alloys. 0.5 wt% γ-Al2O3 nanoparticles were added in hyperEutectic Al–20Si–4.5Cu alloy melt and further dispersed through an ultrasonic-cavitation-based technique. The as-cast Al–20Si–4.5Cu–Al2O3 nanocompoSites showed marked enhancements in both ductility and strength. The ductility of Al2O3 nanocompoSite was more than two times higher than that of the monolithic alloy without the nanoparticles. Microstructural analySis with optical and scanning electron microscopy revealed that both the primary and Eutectic Si particles were Significantly refined. The primary Si particles were refined from star shapes to polygon or blocky shapes, and their edges and corners were much smoother. The large plate Eutectic Si particles were also modified into the fine coralline-like ones. The poroSity of alloy was also reduced with the addition of γ-Al2O3 nanoparticles. Study suggests that γ-Al2O3 nanoparticles Simultaneously refine and modify Si particles as well as reduce poroSity in cast Al–20Si–4.5Cu, resulting in unusual ductility enhancement that could have great potential for numerous applications.
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effect of combined addition of cu and aluminum oxide nanoparticles on mechanical properties and microstructure of al 7Si 0 3mg alloy
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2012Co-Authors: Hongseok Choi, Milton Jones, Hiromi KonishiAbstract:In this study, an ultrasonic cavitation based disperSion technique was used to fabricate Al-7Si-0.3Mg alloyed with Cu and reinforced with 1 wt pct Al2O3 nanoparticles, in order to investigate their influence on the mechanical properties and microstructures of Al-7Si-0.3Mg alloy. The combined addition of 0.5 pct Cu with 1 pct Al2O3 nanoparticles increased the yield strength, tenSile strength, and ductility of the as-cast Al-7Si-0.3Mg alloy, mostly due to grain refinement and modification of the Eutectic Si and θ-CuAl2 phases. Moreover, Al-7Si-0.3Mg-0.5Cu-1 pct Al2O3 nanocompoSites after T6 heat treatment showed a Significant enhancement of ductility (increased by 512 pct) and tenSile strength (by 22 pct). The Significant enhancement of properties is attributed to the suppresSion of pore formation and modification of Eutectic Si phases due to the addition of Al2O3 nanoparticles. However, the yield strength of the T6 heat-treated nanocompoSites was limited in enhancement due to a reaction between Mg and Al2O3 nanoparticles.
Wenjun Zhao - One of the best experts on this subject based on the ideXlab platform.
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effect of al 5ti 0 62c 0 2ce master alloy on the microstructure and tenSile properties of commercial pure al and hypoEutectic al 8Si alloy
Metals, 2017Co-Authors: Wanwu Ding, Wenjun Zhao, Haixia Zhang, Tingbiao Guo, Tiandong XiaAbstract:Al-5Ti-0.62C-0.2Ce master alloy was syntheSized by a method of thermal exploSion reaction in pure molten aluminum and used to modify commercial pure Al and hypoEutectic Al-8Si alloy. The microstructure and tenSile properties of commercial pure Al and hypoEutectic Al-8Si alloy with different additions of Al-5Ti-0.62C-0.2Ce master alloy were investigated. The results show that the Al-5Ti-0.62C-0.2Ce alloy was composed of α-Al, granular TiC, lump-like TiAl3 and block-like Ti2Al20Ce. Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min) can Significantly refine macro grains of commercial pure Al into tiny equiaxed grains. The Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 30 min) still has a good refinement effect. The tenSile strength and elongation of commercial pure Al modified by the Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min) increased by roughly 19.26% and 61.83%, respectively. Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min) can Significantly refine both α-Al grains and Eutectic Si of hypoEutectic Al-8Si alloy. The dendritic α-Al grains were Significantly refined to tiny equiaxed grains. The morphology of the Eutectic Si crystals was Significantly refined from coarse needle-shape or lath-shape to short rod-like or grain-like Eutectic Si. The tenSile strength and elongation of hypoEutectic Al-8Si alloy modified by the Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min) increased by roughly 20.53% and 50%, respectively. The change in mechanical properties corresponds to evolution of the microstructure.
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effect of al 5ti c master alloy on the microstructure and mechanical properties of hyperEutectic al 20 Si alloy
Materials, 2014Co-Authors: Wanwu Ding, Tiandong Xia, Wenjun ZhaoAbstract:Al–5Ti–C master alloy was prepared and used to modify hyperEutectic Al–20%Si alloy. The microstructure evolution and mechanical properties of hyperEutectic Al–20%Si alloy with Al–5Ti–C master alloy additions (0, 0.4, 0.6, 1.0, 1.6 and 2.0 wt%) were investigated. The results show that, Al–5Ti–C master alloy (0.6 wt%, 10 min) can Significantly refine both Eutectic and primary Si of hyperEutectic Al–20%Si alloy. The morphology of the primary Si crystals was Significantly refined from a coarse polygonal and star-like shape to a fine polyhedral shape and the grain Size of the primary Si was refined from roughly 90–120 μm to 20–50 μm. The Eutectic Si phases were modified from a coarse platelet-like/needle-like structure to a fine fibrous structure with discrete particles. The Al–5Ti–C master alloy (0.6 wt%, 30 min) still has a good refinement effect. The ultimate tenSile strength (UTS), elongation (El) and Brinell hardness (HB) of Al–20%Si alloy modified by the Al–5Ti–C master alloy (0.6 wt%, 10 min) increased by roughly 65%, 70% and 51%, respectively, due to decreaSing the Size and changing the morphology on the primary and Eutectic Si crystals. The change in mechanical properties corresponds to evolution of the microstructure.
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effect of in Situ γ al2o3 particles on the microstructure of hyperEutectic al 20 Si alloy
Journal of Alloys and Compounds, 2013Co-Authors: Tiandong Xia, Wenjun Zhao, Yefeng Lan, Lu FanAbstract:Abstract In the present study, the effect of in Situ γ-Al 2 O 3 particles on the morphology and Size of the primary and Eutectic Si phases in hyperEutectic Al–20%Si alloy has been investigated. Microstructural analyses demonstrates that in Situ γ-Al 2 O 3 particles Significantly refined primary Si crystals from coarse polygonal and star-like shape to fine blocky shape with smooth edges and corners. The Eutectic Si structure was modified from the coarse acicular structure to fine flake-like morphology that is intermediate between acicular and coral-like fibrous structure. In addition, the modification mechanism of in Situ γ-Al 2 O 3 particles on Al–20%Si alloy was also discussed.
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effect of rare earth cerium addition on the microstructure and tenSile properties of hyperEutectic al 20 Si alloy
Journal of Alloys and Compounds, 2013Co-Authors: Qinglin Li, Wenjun Zhao, Pengfei LiAbstract:Abstract It is well known that the mechanical properties of hyperEutectic Al–Si alloys are influenced by the Size, morphology and distribution of primary and Eutectic Si crystals. In the present work, the microstructure evolution and mechanical properties of hyperEutectic Al–20%Si alloy with rare earth cerium (Ce) additions (0, 0.3, 0.5, 0.8 and 1.0 wt.%) were investigated. The as-cast samples were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalySis (EPMA) with wavelength disperSive spectroscopic (WDS). The microstructural observation showed that primary Si crystals were Significantly refined from coarse polygonal and star-like shape to fine blocky shape with smooth edges and corners, and Eutectic Si phases were modified from coarse platelet-like/needle-like structure to fine fibrous structure and discrete particles with increaSing the addition contents of rare earth Ce. The mechanical properties were investigated by tenSile test with various concentration of Ce. It was found that the ultimate tenSile strength (UTS) and elongation (El) increased by 68.2% and 53.1%, respectively, due to decreaSing of the Size and changing of morphology on primary and Eutectic Si crystals.
Tiandong Xia - One of the best experts on this subject based on the ideXlab platform.
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modification of hyperEutectic al 20 wt Si alloy based on the addition of yttrium and al 5ti 1b modifiers mixing melt
International Journal of Metalcasting, 2019Co-Authors: Jianjun Liu, Dexue Liu, Yefeng Lan, Tiandong XiaAbstract:The effect of the addition of yttrium (Y) and Al–5Ti–1B modifiers mixing melt (3M) on the microstructure and mechanical properties of hyperEutectic Al–20Si alloy was studied in the present work. The as-cast specimens were examined by scanning electron microscope equipped with energy spectrometer, electron probe microanalySis and X-ray diffraction. The results demonstrated that the morphology of primary Si could be refined from coarse irregular star-like/plate-like structures into fine blocks with the addition of 0.6 wt% Y and 1.0 wt% Al–5Ti–1B at 650 °C. The average grain Size of primary Si was reduced from 82 to 29 µm, and the aspect ratio was decreased from 1.81 to 1.47. Similarly, the Eutectic Si structure was modified from coarse needlelike/flake-like structures into fine coral fibrous structures and partial granular structures, with the mean roundness of Eutectic Si decreased from 7.8 to 2.32. In addition, the coarse α-Al dendrites were Significantly refined into the uniform equiaxed dendrites. With the refinement and homogenization of Si phases, the optimal modified alloy obtained the optimal ultimate tenSile strength (UTS) and elongation (EL). The UTS was enhanced from 94 to 154 MPa, and the EL was increased from initial 1.12 to 1.79%. Furthermore, the refinement and modification mechanism of the addition of yttrium and Al–5Ti–1B modifiers mixing melt on Al–20Si alloy were also discussed.
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effect of samarium sm addition on the microstructure and tenSile properties of al 20 Si casting alloy
International Journal of Metalcasting, 2018Co-Authors: Yefeng Lan, Tiandong XiaAbstract:In the present work, the effect of Sm addition (0.2, 0.4, 0.6, and 0.8 wt%) on the microstructure evolution and tenSile properties of as-cast hyperEutectic Al–20%Si alloy were investigated. The scanning electron microscopy, X-ray diffraction (XRD), and electron probe microanalySis with wavelength disperSive spectroscopy (WDS) were used to quantitatively characterize the samples. The results indicated that the primary Si phases were Significantly refined from coarse polygonal and star-like shape to fine block with smooth edges and corners when the addition of Sm increased from 0 to 0.6%. Furthermore, Eutectic Si phases were fully modified from coarse platelet-like/needle-like structure to fine fibrous structure and discrete particles with the addition of 0.6%Sm. However, the primary and Eutectic Si phases became coarser when the level of rare earth Sm reached 0.8%. The analySis of XRD and WDS shows that Sm mainly exists in the form of Al2Si2Sm compounds. In addition, the tenSile properties of as-cast Al–20%Si alloy with different concentrations of Sm were investigated by tenSile test. It was found that the ultimate tenSile strength (UTS) and elongation (EL) gradually enhanced with the increaSing concentration of Sm from 0 to 0.6% due to decrease of the Size and the change of morphology on Si phases. Compared with unmodified Al–20%Si alloy, the UTS and EL values of Al–20%Si alloy with 0.6%Sm were increased by 48.5 and 68.8%, respectively.
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effect of al 5ti 0 62c 0 2ce master alloy on the microstructure and tenSile properties of commercial pure al and hypoEutectic al 8Si alloy
Metals, 2017Co-Authors: Wanwu Ding, Wenjun Zhao, Haixia Zhang, Tingbiao Guo, Tiandong XiaAbstract:Al-5Ti-0.62C-0.2Ce master alloy was syntheSized by a method of thermal exploSion reaction in pure molten aluminum and used to modify commercial pure Al and hypoEutectic Al-8Si alloy. The microstructure and tenSile properties of commercial pure Al and hypoEutectic Al-8Si alloy with different additions of Al-5Ti-0.62C-0.2Ce master alloy were investigated. The results show that the Al-5Ti-0.62C-0.2Ce alloy was composed of α-Al, granular TiC, lump-like TiAl3 and block-like Ti2Al20Ce. Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min) can Significantly refine macro grains of commercial pure Al into tiny equiaxed grains. The Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 30 min) still has a good refinement effect. The tenSile strength and elongation of commercial pure Al modified by the Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min) increased by roughly 19.26% and 61.83%, respectively. Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min) can Significantly refine both α-Al grains and Eutectic Si of hypoEutectic Al-8Si alloy. The dendritic α-Al grains were Significantly refined to tiny equiaxed grains. The morphology of the Eutectic Si crystals was Significantly refined from coarse needle-shape or lath-shape to short rod-like or grain-like Eutectic Si. The tenSile strength and elongation of hypoEutectic Al-8Si alloy modified by the Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min) increased by roughly 20.53% and 50%, respectively. The change in mechanical properties corresponds to evolution of the microstructure.
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effects of the addition of mg on the microstructure and mechanical properties of hypoEutectic al 7 Si alloy
International Journal of Metalcasting, 2017Co-Authors: Tiandong Xia, Yefeng Lan, Tinbiao GuoAbstract:It is well known that the mechanical properties of hypoEutectic Al–Si alloys are influenced by the Size, morphology and distribution of primary α-Al dendrites, Eutectic Si crystals and other intermetallics. In the present work, the effect of Mg addition on the Size and morphology of the primary α-Al dendrites and Eutectic Si phases in Al–7%Si alloy has been investigated. The microstructure of as-cast samples with different Mg content was characterized by scanning electron microscopy. Microstructural analyses demonstrated that primary α-Al was Significantly refined from coarse dendrites to fine equiaxed grain with increaSing the amounts of Mg. In addition, the Eutectic Si structure was modified from coarse needle-like/platelet-like structure to a fine coral-like fibrous structure. The mechanical properties were investigated by tenSile test with various concentrations of Mg. It was found that the ultimate tenSile strength improved by 61% with an increase in Mg content. However, the ductility initially increased by 80% with an increase in Mg content from 0.5 to 1.5%, then it decreased with further increaSing Mg content up to 2.0 and 2.5%. It is due to precipitation of coarse Chinese script Mg2Si phase that leads to the increase in strength and the decrease in ductility.
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effect of al 5ti c master alloy on the microstructure and mechanical properties of hyperEutectic al 20 Si alloy
Materials, 2014Co-Authors: Wanwu Ding, Tiandong Xia, Wenjun ZhaoAbstract:Al–5Ti–C master alloy was prepared and used to modify hyperEutectic Al–20%Si alloy. The microstructure evolution and mechanical properties of hyperEutectic Al–20%Si alloy with Al–5Ti–C master alloy additions (0, 0.4, 0.6, 1.0, 1.6 and 2.0 wt%) were investigated. The results show that, Al–5Ti–C master alloy (0.6 wt%, 10 min) can Significantly refine both Eutectic and primary Si of hyperEutectic Al–20%Si alloy. The morphology of the primary Si crystals was Significantly refined from a coarse polygonal and star-like shape to a fine polyhedral shape and the grain Size of the primary Si was refined from roughly 90–120 μm to 20–50 μm. The Eutectic Si phases were modified from a coarse platelet-like/needle-like structure to a fine fibrous structure with discrete particles. The Al–5Ti–C master alloy (0.6 wt%, 30 min) still has a good refinement effect. The ultimate tenSile strength (UTS), elongation (El) and Brinell hardness (HB) of Al–20%Si alloy modified by the Al–5Ti–C master alloy (0.6 wt%, 10 min) increased by roughly 65%, 70% and 51%, respectively, due to decreaSing the Size and changing the morphology on the primary and Eutectic Si crystals. The change in mechanical properties corresponds to evolution of the microstructure.
Yefeng Lan - One of the best experts on this subject based on the ideXlab platform.
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influences of fe mn and y additions on microstructure and mechanical properties of hypoEutectic al 7 Si alloy
Intermetallics, 2020Co-Authors: Yuqian Zhu, Yefeng Lan, Shang Zhao, Dexue Liu, Guangfei Jian, Qiang Zhang, Hongwei ZhouAbstract:Abstract In this work, the influences of Fe, Mn and Y with various contents on microstructural evolution and mechanical properties of hypoEutectic Al–7%Si alloy were investigated by microscopy technology and tenSile test. The results showed that the complex addition of Al–20%Si-2.5%Fe–2%Mn master alloy and rare earth Y have much better refining effect of need-like Eutectic Si and coarse α-Al dendrites than that of separate addition of master alloy or rare earth Y. Combined additions of 7.0% master alloy and 0.2% Y, the average grain Size was decreased by 89.5% from 483.1 μm to 50.8 μm and secondary dendrite arm spacing (SDAS) was reduced by 46.8% from 26.9 μm to 14.3 μm. Moreover, the coarse flake-like Eutectic Si structure was effectively modified into fine fiber and granular shape. In addition, ultimate tenSile strength (UTS) was improved by 33.3% from 162 MPa to 216 MPa, and elongation (El) value was enhanced by 46.7% from 6.2% to 9.1%. The fracture mode transformed from brittle fracture to ductile fracture.
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modification of hyperEutectic al 20 wt Si alloy based on the addition of yttrium and al 5ti 1b modifiers mixing melt
International Journal of Metalcasting, 2019Co-Authors: Jianjun Liu, Dexue Liu, Yefeng Lan, Tiandong XiaAbstract:The effect of the addition of yttrium (Y) and Al–5Ti–1B modifiers mixing melt (3M) on the microstructure and mechanical properties of hyperEutectic Al–20Si alloy was studied in the present work. The as-cast specimens were examined by scanning electron microscope equipped with energy spectrometer, electron probe microanalySis and X-ray diffraction. The results demonstrated that the morphology of primary Si could be refined from coarse irregular star-like/plate-like structures into fine blocks with the addition of 0.6 wt% Y and 1.0 wt% Al–5Ti–1B at 650 °C. The average grain Size of primary Si was reduced from 82 to 29 µm, and the aspect ratio was decreased from 1.81 to 1.47. Similarly, the Eutectic Si structure was modified from coarse needlelike/flake-like structures into fine coral fibrous structures and partial granular structures, with the mean roundness of Eutectic Si decreased from 7.8 to 2.32. In addition, the coarse α-Al dendrites were Significantly refined into the uniform equiaxed dendrites. With the refinement and homogenization of Si phases, the optimal modified alloy obtained the optimal ultimate tenSile strength (UTS) and elongation (EL). The UTS was enhanced from 94 to 154 MPa, and the EL was increased from initial 1.12 to 1.79%. Furthermore, the refinement and modification mechanism of the addition of yttrium and Al–5Ti–1B modifiers mixing melt on Al–20Si alloy were also discussed.
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effect of samarium sm addition on the microstructure and tenSile properties of al 20 Si casting alloy
International Journal of Metalcasting, 2018Co-Authors: Yefeng Lan, Tiandong XiaAbstract:In the present work, the effect of Sm addition (0.2, 0.4, 0.6, and 0.8 wt%) on the microstructure evolution and tenSile properties of as-cast hyperEutectic Al–20%Si alloy were investigated. The scanning electron microscopy, X-ray diffraction (XRD), and electron probe microanalySis with wavelength disperSive spectroscopy (WDS) were used to quantitatively characterize the samples. The results indicated that the primary Si phases were Significantly refined from coarse polygonal and star-like shape to fine block with smooth edges and corners when the addition of Sm increased from 0 to 0.6%. Furthermore, Eutectic Si phases were fully modified from coarse platelet-like/needle-like structure to fine fibrous structure and discrete particles with the addition of 0.6%Sm. However, the primary and Eutectic Si phases became coarser when the level of rare earth Sm reached 0.8%. The analySis of XRD and WDS shows that Sm mainly exists in the form of Al2Si2Sm compounds. In addition, the tenSile properties of as-cast Al–20%Si alloy with different concentrations of Sm were investigated by tenSile test. It was found that the ultimate tenSile strength (UTS) and elongation (EL) gradually enhanced with the increaSing concentration of Sm from 0 to 0.6% due to decrease of the Size and the change of morphology on Si phases. Compared with unmodified Al–20%Si alloy, the UTS and EL values of Al–20%Si alloy with 0.6%Sm were increased by 48.5 and 68.8%, respectively.
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effects of the addition of mg on the microstructure and mechanical properties of hypoEutectic al 7 Si alloy
International Journal of Metalcasting, 2017Co-Authors: Tiandong Xia, Yefeng Lan, Tinbiao GuoAbstract:It is well known that the mechanical properties of hypoEutectic Al–Si alloys are influenced by the Size, morphology and distribution of primary α-Al dendrites, Eutectic Si crystals and other intermetallics. In the present work, the effect of Mg addition on the Size and morphology of the primary α-Al dendrites and Eutectic Si phases in Al–7%Si alloy has been investigated. The microstructure of as-cast samples with different Mg content was characterized by scanning electron microscopy. Microstructural analyses demonstrated that primary α-Al was Significantly refined from coarse dendrites to fine equiaxed grain with increaSing the amounts of Mg. In addition, the Eutectic Si structure was modified from coarse needle-like/platelet-like structure to a fine coral-like fibrous structure. The mechanical properties were investigated by tenSile test with various concentrations of Mg. It was found that the ultimate tenSile strength improved by 61% with an increase in Mg content. However, the ductility initially increased by 80% with an increase in Mg content from 0.5 to 1.5%, then it decreased with further increaSing Mg content up to 2.0 and 2.5%. It is due to precipitation of coarse Chinese script Mg2Si phase that leads to the increase in strength and the decrease in ductility.
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effect of in Situ γ al2o3 particles on the microstructure of hyperEutectic al 20 Si alloy
Journal of Alloys and Compounds, 2013Co-Authors: Tiandong Xia, Wenjun Zhao, Yefeng Lan, Lu FanAbstract:Abstract In the present study, the effect of in Situ γ-Al 2 O 3 particles on the morphology and Size of the primary and Eutectic Si phases in hyperEutectic Al–20%Si alloy has been investigated. Microstructural analyses demonstrates that in Situ γ-Al 2 O 3 particles Significantly refined primary Si crystals from coarse polygonal and star-like shape to fine blocky shape with smooth edges and corners. The Eutectic Si structure was modified from the coarse acicular structure to fine flake-like morphology that is intermediate between acicular and coral-like fibrous structure. In addition, the modification mechanism of in Situ γ-Al 2 O 3 particles on Al–20%Si alloy was also discussed.
