The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Kazuhiro Nakata - One of the best experts on this subject based on the ideXlab platform.
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improvement of mechanical properties of aluminum die Casting Alloy by multi pass friction stir processing
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: Kazuhiro Nakata, Hidetoshi Fujii, Takuya Tsumura, Tamu KomazakiAbstract:Abstract An improvement in the mechanical properties was accomplished due to the microstructural modification of an aluminum die Casting Alloy by multi-pass friction stir processing (MP-FSP), which is a solid-state microstructural modification technique using a frictional heat and stirring action. The hardness of the MP-FSP sample is about 20 Hv higher than that of the base metal. The tensile strengths of the MP-FSPed specimens were significantly increased to about 1.7 times versus that of the base metal. This is due not only to the disappearance of the cold flake in the base metal, but also to a structural refinement, such as uniform distribution of Si particles. Thus, the application of the MP-FSP is a very effective method for the mechanical improvement of aluminum die Casting Alloys.
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three defect types in friction stir welding of aluminum die Casting Alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: Young Gon Kim, Hidetoshi Fujii, Takuya Tsumura, Tamu Komazaki, Kazuhiro NakataAbstract:For different tool plunge downforces, the optimum FSW conditions of aluminum die Casting Alloy were examined. The higher the tool plunge downforce is, the wider the range of the optimum FSW conditions is. The following three different types of defects are formed, depending on the FSW conditions. (1) A large mass of flash due to the excess heat input; (2) cavity or groove-like defects caused by insufficient heat input; and (3) cavity caused by the abnormal stirring. As for the abnormal stirring, it is clearly seen that the shape of the top part on the advancing side in the stir zone is completely different. For this type of defect, the effect of the tool plunge downforce is small, though the size of the defect due to insufficient heat input significantly decreases with the increasing downforce.
Fernando Carreno - One of the best experts on this subject based on the ideXlab platform.
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influence of the supersaturated silicon solid solution concentration on the effectiveness of severe plastic deformation processing in al 7 wt si Casting Alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: C M Cepedajimenez, J M Garciainfanta, A P Zhilyaev, Oscar Antonio Ruano, Fernando CarrenoAbstract:Abstract A comparative study of room temperature severe plastic deformation (SPD) of a hypoeutectic Al–7 wt.% Si Casting Alloy by high pressure torsion (HPT) and equal channel angular pressing (ECAP) has been performed. Microstructural parameters and microhardness were evaluated in the present work. Three different initial Si solid solution contents have been considered: as cast (C sample, 1.6 wt.% Si), annealed and quenched (Q sample, 1.2 wt.% Si) and annealed and furnace cooled (S sample, 0.7 wt.% Si). The samples processed by ECAP have smaller average Si particle sizes (0.9–1.7 μm), than those for samples processed by HPT (2.4–4.4 μm). The initial supersaturated Si solid solution is the major factor affecting the microstructure and the mechanical properties of the material. Fine deformation-induced Si precipitates from the supersaturated solid solution were responsible of the large grain refinement obtained by both SPD processing methods, which was considerably higher than that reported for pure aluminium. Q samples, processed by both SPD methods, containing an intermediate concentration of Si in solid solution, show the highest hardness due to the finest and most homogeneous microstructure. The finest and homogeneous grain size was ∼0.2 μm for the HPTed and ∼0.4 μm for the ECAPed Q samples.
A P Zhilyaev - One of the best experts on this subject based on the ideXlab platform.
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influence of the supersaturated silicon solid solution concentration on the effectiveness of severe plastic deformation processing in al 7 wt si Casting Alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: C M Cepedajimenez, J M Garciainfanta, A P Zhilyaev, Oscar Antonio Ruano, Fernando CarrenoAbstract:Abstract A comparative study of room temperature severe plastic deformation (SPD) of a hypoeutectic Al–7 wt.% Si Casting Alloy by high pressure torsion (HPT) and equal channel angular pressing (ECAP) has been performed. Microstructural parameters and microhardness were evaluated in the present work. Three different initial Si solid solution contents have been considered: as cast (C sample, 1.6 wt.% Si), annealed and quenched (Q sample, 1.2 wt.% Si) and annealed and furnace cooled (S sample, 0.7 wt.% Si). The samples processed by ECAP have smaller average Si particle sizes (0.9–1.7 μm), than those for samples processed by HPT (2.4–4.4 μm). The initial supersaturated Si solid solution is the major factor affecting the microstructure and the mechanical properties of the material. Fine deformation-induced Si precipitates from the supersaturated solid solution were responsible of the large grain refinement obtained by both SPD processing methods, which was considerably higher than that reported for pure aluminium. Q samples, processed by both SPD methods, containing an intermediate concentration of Si in solid solution, show the highest hardness due to the finest and most homogeneous microstructure. The finest and homogeneous grain size was ∼0.2 μm for the HPTed and ∼0.4 μm for the ECAPed Q samples.
Jian Feng Nie - One of the best experts on this subject based on the ideXlab platform.
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atom probe characterization of plate like precipitates in a mg re zn zr Casting Alloy
Scripta Materialia, 2003Co-Authors: D H Ping, K Hono, Jian Feng NieAbstract:Abstract This paper demonstrates that the three-dimensional atom probe (3DAP) is capable of characterizing nanoscale precipitates in magnesium Alloys. Combined application of 3DAP and transmission electron microscopy reveals that the major precipitate phase in a Mg–2.4wt.%RE–0.4wt.%Zn–0.6wt.%Zr Alloy has an ordered G.P. zone structure and a composition of approximately 3.2 at.% Nd, 1.0 at.% Ce and 1.2 at.% Zn.
Dongdong Zhang - One of the best experts on this subject based on the ideXlab platform.
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microstructures mechanical properties and creep behavior of a mg 3yb 0 6zn 0 4zr Casting Alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2019Co-Authors: Dongdong Zhang, Kai Guan, Qiang Yang, Bo Jiang, Nan Wang, Baishun Li, Deping Zhang, Xinlin LiAbstract:Abstract Microstructures, mechanical properties and creep behavior of a gravity Casting Mg−3Yb−0.6Zn−0.4Zr (wt%) Alloy were investigated. The results indicate that the studied Alloy has smaller grains compared with the conventional Mg−RE based Casting Alloys, and the dominant intermetallic phase is Mg2Yb although minor Mg41Yb5 was also found in grain interior. In addition, the studied Alloy exhibits medium tensile strength but excellent ductility at room temperature. Simultaneously, a complicated serrated flow phenomenon was observed in its flow curves at 150–250 °C. Finally, we found that the studied Alloy exhibits poor creep resistance compared with the conventional Mg−RE based Alloys. This could be mainly attributed to both poor thermal stability Mg2Yb phase and discontinuous intermetallic phase skeleton. Also, based on the analyses of the stress exponent and activation energy as well as microstructural observation, dislocation climb was proposed as the dominated creep mechanisms of the studied Alloy at 180–220 °C and 40–80 MPa.