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Guanghui Min - One of the best experts on this subject based on the ideXlab platform.
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strain dependent constitutive analysis of hot deformation and hot workability of t4 treated Zk60 magnesium Alloy
Metals and Materials International, 2013Co-Authors: Guanghui Min, Bong Sun You, Sung Soo Park, Youngmin KimAbstract:The hot deformation behavior of T4-treated Zk60 magnesium Alloy was investigated in a compression test conducted with a thermo-mechanical simulator at a temperature range of 523 K to 673 K and a strain rate of 0.001 s−1 to 1 s−1. The results show that the flow stress increases as the deformation temperature decreases and the strain rate increases. Strain-dependent constitutive relationships were developed using regression method and artificial neural network, and good agreements between the experimentally measured values and the predicted ones were achieved. The work hardening analysis and onset of dynamic recrystallization (DRX) were investigated. The processing map reveals a domain of DRX at the temperature range of 620–673 K and strain rate range of 0.001–0.01 s−1, with its peak efficiency of 32% at 623 K and 0.001 s−1, which are the optimum values of the parameters for hot working of the T4-treated Zk60 Alloy. The strain level has a great effect on the processing maps and lower temperatures and higher strain rates should be avoided during hot working processes. DRX model indicates that DRX of Zk60 Alloy is controlled by the rate of nucleation, which is slower than the rate of migration.
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Study on the Microstructure and Texture of Warm Rolled Zk60 Magnesium Alloy Sheet
Advanced Materials Research, 2012Co-Authors: Hongmei Chen, Guanghui Min, Yunxue JinAbstract:The microstructure and macrotexture of Zk60 Alloy sheet were investigated through OM and XRD, which were produced by twin roll casting and sequential warm rolling. Microstructure of twin roll cast Zk60 Alloy changed from dendrite structure to fibrous structure with elongated grains and high density shear bands along the rolling direction after warm rolling process at different rolling parameters. The density of shear bands increased with the decreasing of the rolling temperature, or the increasing of per pass rolling reduction. Dynamic recrystallization could be found during the warm rolling process at and above 350oC, and many fine grains could be found in the shear band area. The warm rolled Zk60 Alloy sheet exhibited strong (0001) basal pole texture. The formation of the shear bands tends to cause the basal pole tilt slightly to the transverse direction after warm rolling. The intensity of (0001) pole figure increased with the decreasing of rolling temperature, or the increasing of per pass rolling reduction.
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microstructure and tensile properties of Zk60 Alloy fabricated by simplified rapid solidification powder metallurgy s rs p m process
Journal of Materials Science & Technology, 2010Co-Authors: Zhen Ya Zhang, Shaoqing Wang, Haitao Wang, Guanghui MinAbstract:This study investigated the microstructures and mechanical properties of Zk60 Alloy prepared by a simplified rapid solidification powder metallurgy (RS P/M) processing system (S-RS P/M), which consists of warm press in dry air and hot extrusion. Microstructure characterizations showed that S-RS P/M Alloy consisted of magnesium matrix and oxide stringers of ∼1 μm in width. TEM (transmission electron microscopy) observations illustrated nano-size magnesia particles (10–30 nm) constituted oxide stringer in detail. Due to a relatively higher volume of nano-size magnesia particle produced during S-RS P/M process, 0.2% yield strength of S-RS P/M Zk60 Alloy was found to be as high as 382 MPa, which is 10% higher than that of RS P/M Alloy. The improvement in mechanical properties is mainly attributed to the combination effects of Orowan mechanism and coefficient of thermal expansion (CTE) mismatch because of the approximately same average grain size.
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Microstructure and Tensile Properties of Zk60 Alloy Fabricated by Simplified Rapid Solidification Powder Metallurgy （S-RS P/M） Process
Journal of Materials Science & Technology, 2010Co-Authors: Zhen Ya Zhang, Shaoqing Wang, Haitao Wang, Guanghui MinAbstract:This study investigated the microstructures and mechanical properties of Zk60 Alloy prepared by a simplified rapid solidification powder metallurgy (RS P/M) processing system (S-RS P/M), which consists of warm press in dry air and hot extrusion. Microstructure characterizations showed that S-RS P/M Alloy consisted of magnesium matrix and oxide stringers of ∼1 μm in width. TEM (transmission electron microscopy) observations illustrated nano-size magnesia particles (10–30 nm) constituted oxide stringer in detail. Due to a relatively higher volume of nano-size magnesia particle produced during S-RS P/M process, 0.2% yield strength of S-RS P/M Zk60 Alloy was found to be as high as 382 MPa, which is 10% higher than that of RS P/M Alloy. The improvement in mechanical properties is mainly attributed to the combination effects of Orowan mechanism and coefficient of thermal expansion (CTE) mismatch because of the approximately same average grain size.
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Effect of rolling temperature on microstructure and texture of twin roll cast Zk60 magnesium Alloy
Transactions of Nonferrous Metals Society of China, 2010Co-Authors: Hongmei Chen, Suk Bong Kang, Guanghui Min, Yunxue JinAbstract:Abstract Twin roll cast Zk60 Alloy strip/sheet with final thickness of 0.5 mm was prepared, and effect of rolling temperature on microstructure and texture development was investigated using OM and XRD technique, microstructure and texture were measured on specimens subjected to rolling experiment at different rolling temperature, and macrotexture was also evaluated by X-ray diffraction method. In addition, the (10 0) and (0002) pole figures were measured, and the tensile test was performed to reveal the influence of rolling temperature on mechanical properties. The results show that the microstructure of Zk60 Alloy sheet consisted of fibrous structure with elongated grains, and shear bands along the rolling direction after warm rolling. Dynamic recrystallization could be found during the warm rolling process at rolling temperature 350 °C and above. And many fine recrystallized grain could be observed in the shear bands area. It is a little difficult to see the recrystallized grain in the sheet warm rolled at 300 °C because of higher density of shear bands. The warm rolled Zk60 Alloy sheet exhibited strong (0002) pole texture, the intensity of (0002) pole figure decreases with the increasing of rolling temperature and the basal pole tilted slightly to the transverse direction after warm rolling.
Terence G. Langdon - One of the best experts on this subject based on the ideXlab platform.
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An investigation of the limits of grain refinement after processing by a combination of severe plastic deformation techniques: a comparison of Al and Mg Alloys
Materials Science and Engineering: A, 2018Co-Authors: Shima Sabbaghianrad, Seyed Alireza Torbati-sarraf, Terence G. LangdonAbstract:Abstract An Al-7075 aluminum Alloy and a Zk60 magnesium Alloy were processed by a combination of equal-channel angular pressing (ECAP) for 4 passes and high-pressure torsion (HPT) through total numbers of up to 20 turns. Processing by ECAP and HPT were performed at 473 K and room temperature, respectively. Mechanical testing showed an increase in the hardness value of the Al-7075 Alloy after a combination of ECAP and HPT whereas in the Zk60 Alloy the hardness was reduced. Microstructural images of the Al-7075 Alloy revealed very significant grain refinement after a combination of ECAP + HPT compared to the individual processing techniques. By contrast, and consistent with the hardness measurements, the average grain size of the Zk60 Alloy was larger after processing by the two-step SPD technique. These results are examined and an explanation is presented based on the available microstructural evidence.
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evolution of texture in a magnesium Alloy processed by ecap through dies with different angles
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010Co-Authors: Roberto B. Figueiredo, Terence G. Langdon, Irene J Beyerlein, Alexander P ZhilyaevAbstract:A fine-grained magnesium Zk60 Alloy was used to study texture evolution during processing by equalchannel angular pressing. Experiments were conducted by pressing the Alloy through dies having angles of 90◦, 110◦ and 135◦ and the textures were predicted using a visco-plastic self-consistent model. It is shown that the development of texture depends upon the channel angle within the die. Calculations
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Factors influencing superplastic behavior in a magnesium Zk60 Alloy processed by equal-channel angular pressing
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: Roberto B. Figueiredo, Terence G. LangdonAbstract:Processing by equal-channel angular pressing was used to refine the grain size of a magnesium Zk60 Alloy to ∼0.8 μm and introduce a superplastic capability. Superplastic elongations up to >1000% were achieved at temperatures of 450 and 473 K but the superplastic behavior was lost at 493 K because of grain growth. The strain rate sensitivity under optimum superplastic conditions was measured as ∼0.5 which is consistent with conventional superplastic flow.
Fu Sheng Pan - One of the best experts on this subject based on the ideXlab platform.
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Effect of Compressive Deformation on Wear Property of Extruded Zk60 Magnesium Alloy
Tribology Transactions, 2018Co-Authors: Gui-lin Gong, Fu Sheng Pan, Guangsheng Huang, Huang Lun, Bin JiangAbstract:The present study investigates the dry sliding wear behavior of precompressed Zk60 Alloy using a ball-on-disc wear test machine under normal loads of 20 and 40N at a sliding speed of 0.5m s−1 for a...
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The yield asymmetry and precipitation behavior of pre-twinned Zk60 Alloy
Materials Science and Engineering: A, 2016Co-Authors: Hongbing Chen, Tianmo Liu, Yin Zhang, Bo Song, Dewen Hou, Fu Sheng PanAbstract:Abstract This study aims to investigate the tension and compression properties and precipitation behavior of pre-twinned Zk60 Alloys. It was found that aging treatment can effectively reduce the tension–compression yield asymmetry of pre-twinned Zk60 Alloy. For the pre-twinned sample with 10 h aging treatment, the yield asymmetry ratio is nearly equal to 1. Precipitate behavior in {10–12} extension twins of Zk60 Mg Alloy were characterized by TEM. Three different morphologies of precipitates, [0001] twin rods, (0001) twin plates and [11–20] twin laths were observed in {10–12} extension twins. The precipitates constituted Mg 4 Zn 7 or MgZn 2 phases. The Mg 4 Zn 7 phases have two variant orientations of the [010] zone axis, [010] Mg4Zn7 ‖ [0001] twin and (−201) Mg4Zn7 ‖ (‐12‐10) twin or (−201) Mg4Zn7 ‖ (10–10) twin , while the MgZn 2 phases have an orientation of [‐12‐10] MgZn2 ‖ [0001] twin and (10–12) MgZn2 ‖ (10–10) twin . [11–20] twin laths as a new morphology of the precipitates have been found in Zk60 Alloy, which have an orientation relationship of [010] Mg4Zn7 ‖ [0001] twin and (−201) Mg4Zn7 ‖ (‐12‐10) twin . Finally, the influences of aging treatment on yield asymmetry of pre-twinned Zk60 Alloy are addressed and discussed.
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Enhanced Electromagnetic Interference Shielding of Mg–Zn–Zr Alloy by Ce Addition
Acta Metallurgica Sinica (English Letters), 2015Co-Authors: Xianhua Chen, Lizi Liu, Juan Liu, Fu Sheng PanAbstract:The effects of Ce addition on microstructure and electromagnetic interference (EMI) shielding response of Mg–6Zn–0.5Zr (Zk60) Alloy have been investigated. Ce addition resulted in grain refinement and higher density of Mg–Zn–Ce and MgZn2 intermetallic particles in the Alloy. In particular, this was substantially remarkable as the addition of Ce was up to 1.0 wt%. It is interesting to note that as-extruded Zk60 Alloy with 1.0 wt% Ce addition exhibited an EMI shielding effectiveness (SE) exceeding 70 dB at the frequency range of 30–1,500 MHz, which was significantly higher than that of Zk60 Alloy without Ce addition and reached the requirement of high protection. The superior SE was probably related to the increased reflection and multiple reflection of electromagnetic radiation induced by Ce addition. Direct artificial aging at 150 °C for 25 or 50 h led to a further increase of 7–10 dB in the SE of the Alloy with 1.0 wt% Ce addition. The advantages of excellent shielding capacity and favorable mechanical strength make the Mg–Zn–Zr–Ce Alloy an attractive shielding candidate material for a variety of technological applications.
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Microstructures and mechanical properties of Zk60 Alloy containing Sc
Materials Research Innovations, 2014Co-Authors: Ting Ting Liu, Ai Tao Tang, Ning Guo, Fu Sheng PanAbstract:This work examined the effects of Sc addition of 0·7–1·3 wt.% on the microstructure and tensile properties of Zk60 Alloy. The investigation showed that the Sc3Zn17 intermetallic compound was present in the as cast Zk60 Alloy with the addition of Sc. After the hot extrusion, the degree of recrystallisation was decreased with the increasing of Sc content and the recrystallised grains were effectively refined due to the presence of Sc solute and particles in the grain boundaries which led to the significant improvement of the ultimate and yield strength of Zk60 Alloy with Sc addition at room temperature. Furthermore, the addition of Sc to Zk60 Alloy sharpened the extrusion texture.
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Mechanical properties and electromagnetic shielding effectiveness of Zk60 magnesium Alloy subjected to cold rolling and aging
Materials Research Innovations, 2014Co-Authors: Xi Chen, Fu Sheng Pan, L. Liu, L. QiaoAbstract:Mechanical properties and electromagnetic interference (EMI) shielding effectiveness (SE) of extruded Zk60 Alloy after pre-cold rolling and artificial aging treatment were investigated. Tensile testing was employed to evaluate the mechanical properties, and the EMI shielding property was measured by the coaxial cable method at ambient temperature. High densities of second phase precipitates and deformation twins were observed in the treated Zk60 Alloys. Experimental results show that the specimens subjected to cold rolling and aging treatment possess remarkably improved mechanical strength and EMI SE compared with the extruded specimen. Artificial aging at 150°C for 15 h after cold rolling is determined to be the optimum heat treatment condition, which results in a yield strength increase in 103 MPa and an SE enhancement of 15–20 dB in the testing frequency range 30–1500 MHz. The above mentioned observations are analysed in terms of abundant defects and MgZn2 phase precipitation in the Zk60 Alloy.
Erenilton Pereira Da Silva - One of the best experts on this subject based on the ideXlab platform.
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Hydrogen storage properties of filings of the Zk60 Alloy modified with 2.5 wt% mischmetal
International Journal of Hydrogen Energy, 2020Co-Authors: Erenilton Pereira Da Silva, Verona Biancardi Oliveira, Haroldo Cavalcanti Pinto, Daniel Rodrigo Leiva, Ricardo Floriano, Walter José BottaAbstract:Abstract In this study, a commercial Mg-based Zk60 Alloy was modified with 2.5 wt% mischmetal (Zk60-2.5 wt%Mm) and further processed by cold rolling followed by manual filing. The chips obtained by manual filing process were collected from the as cast (AC) and the cold rolled (CR) materials. The hydrogen storage properties were evaluated by kinetics measurements at 350 °C. A full microstructural characterization including optical, scanning and transmission electron microscopy (MO, MEV and TEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) was performed in the samples. For the first absorption of both filed samples the H storage capacity showed a value around 6.0 wt% after 1 h while for the CR sample it was close to 1.25 wt% after the same time. The manual filing produced samples with higher hydrogenation kinetics compared with that of the CR sample. Besides, their hydrogen storage capacity was maintained close to the theoretical value (6.75 wt%). The breakage and pulverization of the intermetallic phases gave the chips from the CR Alloy the faster hydrogenation kinetics, especially for H-desorption.
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Effect of Ce-base mischmetal addition on the microstructure and mechanical properties of hot-rolled Zk60 Alloy
Journal of Magnesium and Alloys, 2020Co-Authors: Erenilton Pereira Da Silva, Ricardo Henrique Buzolin, F. Marques, Flavio Soldera, U. Alfaro, Haroldo Cavalcanti PintoAbstract:Abstract Mg-Zn-Zr (ZK) Alloys exhibit notably high mechanical strength amongst all magnesium Alloy grades. However, due to the formation of low melting point Mg3Zn7-precipitates, these Alloys are susceptible to hot cracking, thus compromising their metallurgical processing. The addition of rare earths to ZK Alloys is an alternative to form higher melting point intermetallic compounds, speed up dynamic recrystallization, refine grain size, enhance corrosion resistance and extend the service temperature due to improved creep resistance. This work deals with the effect of Ce-base mischmetal addition on the hot rolling behaviour of as-cast Zk60 Alloy. The microstructure investigation conducted using electron microscopy and X-Ray diffraction shows that precipitation of Mg7Zn3 intermetallics occur during hot rolling, whereas no further precipitation is observed for the Zk60-Mm Alloys. The fragmentation of the intermetallic compounds occur during hot rolling and finer particles of Mg7Zn3 are observed for the Zk60, whereas Mg7Zn3 and MgZn2Ce intermetallics are formed in the Alloy modified with mischmetal addition. A higher fraction of dynamically recrystallized grains is observed for the Zk60-Mm in comparison to the Zk60. Continuous recrystallization takes place in Zk60 with the formation of sub-grains near to the intermetallics and the addition of mischmetal promotes the occurrence of discontinuous recrystallization with the nucleation of new grains close to the precipitates. The mechanical strength and, in particular, the ductility of the hot-rolled Alloys are notably improved when compared to the same Alloys in the as-cast condition. The mechanical strength is, however, higher for the Zk60 Alloy. Less solid solution strengthening, softer MgZn2Ce intermetallics and more extensive recrystallization contribute to reduce the mechanical strength of Zk60-Mm. Failure in both Alloys are initiated at coarse intermetallics and propagate through intermetallic-rich regions.
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corrosion behavior of as cast Zk60 Alloy modified with rare earth addition in sodium sulfate medium
Corrosion Science, 2019Co-Authors: Verona Biancardi Oliveira, Luccas Rosa Viera, Bruno De Abreu Lima, Pedro Renato Tavares Avila, Galtiere Correa Rego, Ivan Napoleao Bastos, H Pinto, Erenilton Pereira Da SilvaAbstract:Abstract The corrosion resistance of the as-cast Zk60 Alloy with and without 1.5 %wt rare earth (RE) addition and submitted to a dip sol-gel coating was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 0.1 mol/L Na 2 SO 4 solution. Analysis using scanning Kelvin probe force microscopy (SKPFM) was carried out to investigate the corrosion attack mechanism on these Alloys. The RE addition has accelerated the Zk60 Alloy dissolution by formation of a less noble RE-rich second phase. The dip sol-gel coating was not confirmed as a powerful tool to enhance the protection against corrosion in the as-cast Zk60 Alloys.
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Effects of friction stir processing on hydrogen storage of Zk60 Alloy
International Journal of Hydrogen Energy, 2018Co-Authors: Erenilton Pereira Da Silva, Haroldo Cavalcanti Pinto, Daniel Rodrigo Leiva, Ricardo Floriano, A.m. Neves, Walter José BottaAbstract:Abstract In this paper we report the use of a novel processing route to produce samples for use as a hydrogen carrier. Zk60 Alloy was produced by induction melting and sheets taken from the melt ingot were submitted to Friction Stir Processing (FSP) and subsequent manual filing with a rasp under ambient conditions. Samples from the Base Metal As-Cast (AC) and Stir Zone (SZ) were microstructurally investigated before and after filing including the Alloy in as-cast state. The results showed that before filing SZ and AC samples presented equiaxial grains with the SZ sample having a much finer microstructure compared to AC. The values of grain sizes are around 150 μm and 1–2 μm for the AC and SZ samples, respectively. After filing, both samples presented similar grain sizes of only 60 nm. Although they attained similar grain sizes, the filings from SZ were more homogeneous and presented thinner innerlayers compared to its AC counterpart. The filings taken out from the SZ presented much faster kinetics for hydrogen absorption mainly due to its thinner innerlayers and its finer second-phase particle distribution, reaching up to 4.5 wt% of hydrogen uptake against only 1.0 wt% for AC sample after 10 h of absorption in the first cycle. Both samples presented similar behavior for full discharge time. These results show the possibility of using FSP with subsequent filing as a mean to obtain materials with suitable properties for use as energy carriers with enhanced kinetics and better oxidation resistance in shorter processing times.
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Impact of Ce-base mischmetal on the microstructure and mechanical behavior of Zk60 magnesium casting Alloys
Materials Science and Engineering: A, 2018Co-Authors: Erenilton Pereira Da Silva, F. Marques, U. Alfaro, T.s. Nossa, Haroldo Cavalcanti PintoAbstract:Abstract Magnesium Alloys are important alternatives for structural weight reduction due to their low density and good specific mechanical strength. Among the magnesium Alloys, the ZK type exhibits the highest mechanical strength. However, it has limitations on hot working or welding owing to the presence of intermetallics with low melting point and consequently susceptibility to hot crack formation. The addition of rare earths tends to form intermetallics with higher melting points, thus inhibiting the formation of hot cracks, as well as building up thin and dense surface films that improve corrosion resistance. This work studies the addition of 1.5% wt. of mischmetal (Mm) to the Zk60 Alloy, and then demonstrates the effects of the casting process with mechanical mixing in the semi-solid state. The Alloys produced were: Zk60 and Zk60–1.5 wt%Mm manufactured by conventional casting and rheocast Zk60–1.5 wt%Mm produced with mechanical mixing in the semi-solid state. The casting and cooling methods result in defect-free and chemically homogeneous materials, and the mechanical mixing provides a homogeneous microstructure with globular grains. The mechanical strength was though higher for the Zk60 Alloy due to its increased solute content within the Mg-matrix and the smaller quantity of intermetallics that builds up an intermittent network. The Mg7Zn3 intermetallic, which is the main precipitate for Zk60 Alloy, has hardness 20% higher than the MgZn2Ce intermetallic that is precipitated with the mischmetal addition and partly removes solute from the Mg-solid solution.
Hongmei Chen - One of the best experts on this subject based on the ideXlab platform.
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Effect of addition of small amounts of samarium on microstructural evolution and mechanical properties enhancement of an as-extruded Zk60 magnesium Alloy sheet
Journal of Materials Research and Technology, 2020Co-Authors: Tiantian Zhang, Hongmei Chen, Hongwei Cui, Xiaoli Cui, Ertuan Zhao, Lili Chang, Yaokun Pan, Rui Feng, Shenbao Zhai, Shaochun ChaiAbstract:Abstract The microstructure, texture evolution and mechanical properties of as-extruded Mg-5.5Zn-0.8Zr (wt.%) (Zk60) Alloy with 1 % Sm addition were investigated. The results showed that the as-extruded Zk60-1Sm Alloy consisted of α-Mg, Mg2Zn3, Mg7Zn3, Mg41Sm5 and (Mg, Zn)3Sm phases. The addition of 1 %Sm precipitated the Mg41Sm5 and (Mg, Zn)3Sm phases, which promoted the dynamic recrystallization (DRX) in the subsequent extrusion process and resulted in grain refinement. The microtexture and the orientation distribution characteristic implied that large amounts of and slips were activated in Zk60-1Sm Alloy during extrusion process, while only basal slip was observed in Zk60 Alloy. The non-basal slips led to more potential nucleation sites and a better coordination for the deformation, resulting in the better comprehensive mechanical properties of the as-extruded Zk60-1Sm sheet. Meanwhile, the as-extruded Zk60-1Sm Alloy showed higher strength and ductility compared to Zk60 Alloy. The ultimate tensile strength (UTS), the yield strength (YS) and the elongation to failure (EL) along the extrusion direction (ED) were enhanced by 11.7 %, 24.5 % and 26.2 %, respectively. The influence of fine grain microstructure, nanoscale Mg41Sm5 phase, micron scale (Mg, Zn)3Sm phase and texture evolution, contributed mainly to the strength of as-extruded Zk60-1Sm Alloy.
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Effect of hot rolling on microstructure and damping capacity of Twin Roll Cast Zk60 Alloy
Materials Research Innovations, 2015Co-Authors: Qianhao Zang, Hongmei Chen, Jing Zhang, J. H. Cho, Yunxue Jin, Y. K. ShiAbstract:AbstractZk60 Alloy strip with 3·5 mm thickness which produced by Twin Roll Casting (TRC) was used in this paper. The effect of hot rolling and sequential annealing on microstructure and damping capacity of the Zk60 Alloy was studied by using optical microscope (OM) and dynamic mechanical analyzer (DMA). The dendrite structure was present in TRC Zk60 Alloy strip before and after annealing heat treatment. The small and equiaxed recrystallised grains were obtained after annealing at 350°C for 103 s in hot rolled Zk60 Alloy sheet. The hot rolling and the sequential annealing improved the room temperature mechanical properties and damping capacity of TRC Zk60 Alloy. The tensile strength, yield strength and elongation of as-annealed TRC Zk60 Alloy strip and hot rolled Zk60 Alloy sheet were 207, 184 MPa, 2·6% and 418, 349 MPa, 18·6%, respectively. The room temperature damping value (Q− 1) of Zk60 strip and Zk60 Alloy sheet after annealing heat treatment was 0·0085 and 0·0119, respectively. The damping peaks were...
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Effect of Annealing Temperature on Microstructure and Damping Capacity of Twin Roll Cast Zk60 Alloy
Advanced Materials Research, 2015Co-Authors: Qianhao Zang, Hongmei Chen, Jing Zhang, Y. K. Shi, Yunxue JinAbstract:Zk60 Alloy strip with 3.5mm thickness which produced by Twin Roll Casting (designated as TRC in short) was used in this paper. The effect of sequential annealing on microstructure and damping capacity of TRC Zk60 Alloy was studied by using optical microscope (OM) and dynamic mechanical analyzer (DMA). The dendrite structure was present in TRC Zk60 Alloy strip before and after annealing heat treatment. A few of recrystallized grains were present after annealed at 400°C for 1hr. The damping capacity of the strip as annealed at 400°C was better than that of annealed at the lower temperature. The room temperature (25°C) damping values (Q-1) of Zk60 strip which was annealed at 300°C, 350°C and 400°C were 0.0079, 0.0085 and 0.0096, respectively. The damping peak P1 is a relaxation process, but the damping peak P2 is not a relaxation process. The activation energy H for P1 of TRC Zk60 strip after annealed at 400°C for 1hr was 114KJ/mol. The damping peak P1 was attributed to boundary slip controlled by grain boundary diffusion and lattice self-diffusion.
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Study on the Microstructure and Texture of Warm Rolled Zk60 Magnesium Alloy Sheet
Advanced Materials Research, 2012Co-Authors: Hongmei Chen, Guanghui Min, Yunxue JinAbstract:The microstructure and macrotexture of Zk60 Alloy sheet were investigated through OM and XRD, which were produced by twin roll casting and sequential warm rolling. Microstructure of twin roll cast Zk60 Alloy changed from dendrite structure to fibrous structure with elongated grains and high density shear bands along the rolling direction after warm rolling process at different rolling parameters. The density of shear bands increased with the decreasing of the rolling temperature, or the increasing of per pass rolling reduction. Dynamic recrystallization could be found during the warm rolling process at and above 350oC, and many fine grains could be found in the shear band area. The warm rolled Zk60 Alloy sheet exhibited strong (0001) basal pole texture. The formation of the shear bands tends to cause the basal pole tilt slightly to the transverse direction after warm rolling. The intensity of (0001) pole figure increased with the decreasing of rolling temperature, or the increasing of per pass rolling reduction.
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Effect of rolling temperature on microstructure and texture of twin roll cast Zk60 magnesium Alloy
Transactions of Nonferrous Metals Society of China, 2010Co-Authors: Hongmei Chen, Suk Bong Kang, Guanghui Min, Yunxue JinAbstract:Abstract Twin roll cast Zk60 Alloy strip/sheet with final thickness of 0.5 mm was prepared, and effect of rolling temperature on microstructure and texture development was investigated using OM and XRD technique, microstructure and texture were measured on specimens subjected to rolling experiment at different rolling temperature, and macrotexture was also evaluated by X-ray diffraction method. In addition, the (10 0) and (0002) pole figures were measured, and the tensile test was performed to reveal the influence of rolling temperature on mechanical properties. The results show that the microstructure of Zk60 Alloy sheet consisted of fibrous structure with elongated grains, and shear bands along the rolling direction after warm rolling. Dynamic recrystallization could be found during the warm rolling process at rolling temperature 350 °C and above. And many fine recrystallized grain could be observed in the shear bands area. It is a little difficult to see the recrystallized grain in the sheet warm rolled at 300 °C because of higher density of shear bands. The warm rolled Zk60 Alloy sheet exhibited strong (0002) pole texture, the intensity of (0002) pole figure decreases with the increasing of rolling temperature and the basal pole tilted slightly to the transverse direction after warm rolling.
