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155 results on '"Qiao, X.G."'

38. In-situ synchrotron diffraction study on compressive deformation behavior of Mg92Y5Ni3 alloy mostly composed of LPSO

Author

National Natural Science Foundation of China, Wu, S.Z., Chi, Y.Q., Xie, W.C., Garcés, Gerardo, Zhou, X.H., Brokmeier, H.G., Qin, S.H., Qiao, X.G., Zheng, M.Y., National Natural Science Foundation of China, Wu, S.Z., Chi, Y.Q., Xie, W.C., Garcés, Gerardo, Zhou, X.H., Brokmeier, H.G., Qin, S.H., Qiao, X.G., and Zheng, M.Y.

Abstract

The compressive deformation behavior of the as-cast and as-extruded MgYNi (at.%) alloy mostly composed of long period stacking ordered (LPSO) phase was studied by in-situ synchrotron radiation combined with the analysis of deformation traces after compression at different applied stress. The as-cast alloy has random texture, while the as-extruded alloy has a typical basal texture with basal plane parallel to extrusion (compression) direction. Prior to macro-yielding, some softly oriented grains are preferentially plastically deformed, leading to micro-yielding. The micro-yielding behavior of both as-cast and as-extruded alloys is controlled by basal slip, the as-extruded alloy has higher micro-yielding strength than the as-cast alloy. The activated deformation mode near the macro-yielding point is prismatic slip in both as-cast and as-extruded alloys, and as the hard oriented grains dominate in the as-extruded alloy, the compressive yield strength of the alloy is increased from 217 MPa to 535 MPa after extrusion. The kinking activated following the prismatic slip can introduce a large number of dislocations in the as-extruded alloy, resulting in high strain-hardening rate of 3000 MPa, high ultimate compressive strength of ∼800 MPa and plastic strains above 10%.

Published
2022

39. Role of extrusion rate on the microstructure and tensile properties evolution of ultrahigh-strength low-alloy Mg-1.0Al-1.0Ca-0.4Mn (wt.%) alloy.

Author

Liu, X.Q., Qiao, X.G., Pei, R.S., Chi, Y.Q., Yuan, L., and Zheng, M.Y.

Subjects
TENSILE strength, MICROSTRUCTURE, STRAIN hardening, CRYSTAL grain boundaries, ALLOYS, MAGNESIUM alloys, FIBERS
Abstract

Mg-1.0Al-1.0Ca-0.4Mn (AXM1104, wt.%) low alloy was extruded at 200 °C with an extrusion ratio of 25 and different ram speeds from 1.0 to 7.0 mm/s. The influence of extrusion rate on microstructure and mechanical properties of the AXM1104 alloy was systematically studied. With the increasing of extrusion rate, the mean dynamically recrystallized (DRXed) grain size of the low alloy and average particles diameter of precipitate second phases were increased, while the degree of grain boundary segregation and the intensity of the basal fiber texture were decreased. With the rising of extrusion rate from 1.0 to 7.0 mm/s, the tensile yield strength (TYS) of the as-extruded AXM1104 alloy was decreased from 445 MPa to 249 MPa, while the elongation to failure (EL) was increased from 5.0% to 17.6%. The TYS, ultimate tensile strength (UTS) and EL of the AXM1104 alloy extruded at the ram speed of 1.5 mm/s was 412 MPa, 419 MPa and 12.0%, respectively, exhibiting comprehensive tensile mechanical properties with ultra-high strength and excellent plasticity. The ultra-high TYS of 412 MPa was mainly due to the strengthening from ultra-fine DRXed grains with segregation of solute atoms at grain boundaries. The strain hardening rate is increase slightly with increasing extrusion speed, which may be ascribed to the increasing mean DRXed grain size with rising extrusion speed. The higher strain hardening rate contributes to the higher EL of these AXM1104 samples extruded at higher ram speed. [ABSTRACT FROM AUTHOR]

Published
2023
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