Based on the deforming technique of severe plastic deformation(SPD), the grain refinement of a Mg-9Gd-3Y-2Zn-0.5Zr alloy treated with decreasing temperature reciprocating upsetting-extrusion(RUE) and its influence on ...Based on the deforming technique of severe plastic deformation(SPD), the grain refinement of a Mg-9Gd-3Y-2Zn-0.5Zr alloy treated with decreasing temperature reciprocating upsetting-extrusion(RUE) and its influence on the mechanical properties and wear behavior of the alloy were studied. The RUE process was carried out for 4 passes in total, starting at 0 ℃ and decreasing by 10 ℃ for each pass. The results showed that as the number of RUE passes increased, the grain refinement effect was obvious, and the second phase in the alloy was evenly distributed. Room temperature tensile properties of the alloy and the deepening of the RUE degree showed a positive correlation trend, which was due to the grain refinement, uniform distribution of the second phase and texture weakening. And the microhardness of the alloy showed that the microhardness of RUE is the largest in 2 passes. The change in microhardness was the result of dynamic competition between the softening effect of DRX and the work hardening effect. In addition, the wear resistance of the alloy showed a positive correlation with the degree of RUE under low load conditions. When the applied load was higher, the wear resistance of the alloy treated with RUE decreased compared to the initial state alloy. This phenomenon was mainly due to the presence of oxidative wear on the surface of the alloy, which could balance the positive contribution of severe plastic deformation to wear resistance to a certain extent.展开更多
The microstructure, mechanical properties and fracture behavior of sand-cast Mg-10Gd-3Y-0.5Zr alloy （mass fraction,%） under T6 condition （air cooling after solid solution and then aging heat treatment） were invest...The microstructure, mechanical properties and fracture behavior of sand-cast Mg-10Gd-3Y-0.5Zr alloy （mass fraction,%） under T6 condition （air cooling after solid solution and then aging heat treatment） were investigated. The optimum T6 heat treatments for sand-cast Mg-10Gd-3Y-0.5Zr alloy are （525 ℃, 12 h＋225 ℃, 14 h） and （525 ℃, 12 h＋250 ℃, 12 h） according to age hardening curve and mechanical properties, respectively. The ultimate tensile strength, yield strength and elongation of the Mg-10Gd-3Y-0.5Zr alloy treated by the two optimum T6 processes are 339.9 MPa, 251.6 MPa, 1.5%and 359.6 MPa, 247.3 MPa, 2.7%, respectively. The tensile fracture mode of peak-aged Mg-10Gd-3Y-0.5Zr alloy is transgranular quasi-cleavage fracture.展开更多
The effect of the cooling rate ranging from 1.4 °C/s to 3.5 °C/s on the solidification behavior of the sand-cast Mg?10Gd?3Y?0.4Zr alloy was studied by computer aided cooling curve analysis (CA-CCA). With the...The effect of the cooling rate ranging from 1.4 °C/s to 3.5 °C/s on the solidification behavior of the sand-cast Mg?10Gd?3Y?0.4Zr alloy was studied by computer aided cooling curve analysis (CA-CCA). With the increase in cooling rate, the nucleation temperature (Tα,N) increases from 634.8 °C to 636.3 °C, the minimum temperature (Tα,Min) decreases from 631.9 °C to 630.7 °C, the nucleation undercooling (ΔTN) increases from 2.9 °C to 5.6 °C, the beginning temperature of the eutectic reaction (Teut,N) increases, the time of the eutectic reaction shortens, solidus temperature decreases from 546.0 °C to 541.4 °C, and solidification temperature range (ΔTS) increases by 6.1 °C. The increased nucleation rate (N&) is supposed to be the main reason for the increased?TN. Increased value (Teut,N?Teut,G) and shortened time of the eutectic reaction cause the change in the volume fraction and morphology of the second phase.展开更多
基金National Natural Science Foundation of China(Nos.U2037601,51821001)Key Basic Research Project of the National Basic Strengthening Plan,China(No.2022-xxxx-ZD-093-xx)。
基金financially supported by the Natural Science Foundation of Shanxi Province (No. 201901D111176)the Joint Funds of the National Natural Science Foundation of china (Grant No. U20A20230)+3 种基金the Bureau of science, technology and industry for National Defense of China (No. WDZC2019JJ006)the Key R&D program of Shanxi Province (International Cooperation) (No. 201903D421036)the National Natural Science Foundation of China (Grant No. 52075501)Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi (No. 2018002)。
文摘Based on the deforming technique of severe plastic deformation(SPD), the grain refinement of a Mg-9Gd-3Y-2Zn-0.5Zr alloy treated with decreasing temperature reciprocating upsetting-extrusion(RUE) and its influence on the mechanical properties and wear behavior of the alloy were studied. The RUE process was carried out for 4 passes in total, starting at 0 ℃ and decreasing by 10 ℃ for each pass. The results showed that as the number of RUE passes increased, the grain refinement effect was obvious, and the second phase in the alloy was evenly distributed. Room temperature tensile properties of the alloy and the deepening of the RUE degree showed a positive correlation trend, which was due to the grain refinement, uniform distribution of the second phase and texture weakening. And the microhardness of the alloy showed that the microhardness of RUE is the largest in 2 passes. The change in microhardness was the result of dynamic competition between the softening effect of DRX and the work hardening effect. In addition, the wear resistance of the alloy showed a positive correlation with the degree of RUE under low load conditions. When the applied load was higher, the wear resistance of the alloy treated with RUE decreased compared to the initial state alloy. This phenomenon was mainly due to the presence of oxidative wear on the surface of the alloy, which could balance the positive contribution of severe plastic deformation to wear resistance to a certain extent.
基金Project(51275295)supported by the National Natural Science Foundation of ChinaProject(USCAST2012-15)supported by the Funded Projects of SAST-SJTU Joint Research Centre of Advanced Aerospace Technology,ChinaProject(20120073120011)supported by the Research Fund for the Doctoral Program of Higher Education of China
文摘The microstructure, mechanical properties and fracture behavior of sand-cast Mg-10Gd-3Y-0.5Zr alloy （mass fraction,%） under T6 condition （air cooling after solid solution and then aging heat treatment） were investigated. The optimum T6 heat treatments for sand-cast Mg-10Gd-3Y-0.5Zr alloy are （525 ℃, 12 h＋225 ℃, 14 h） and （525 ℃, 12 h＋250 ℃, 12 h） according to age hardening curve and mechanical properties, respectively. The ultimate tensile strength, yield strength and elongation of the Mg-10Gd-3Y-0.5Zr alloy treated by the two optimum T6 processes are 339.9 MPa, 251.6 MPa, 1.5%and 359.6 MPa, 247.3 MPa, 2.7%, respectively. The tensile fracture mode of peak-aged Mg-10Gd-3Y-0.5Zr alloy is transgranular quasi-cleavage fracture.
基金Project(51275295)supported by the National Natural Science Foundation of ChinaProject(USCAST2012-15)supported by the SAST-SJTU Joint Research Centre of Advanced Aerospace Technology,ChinaProjects(20120073120011,20130073110052)supported by the Research Fund for the Doctoral Program of Higher Education of China
文摘The effect of the cooling rate ranging from 1.4 °C/s to 3.5 °C/s on the solidification behavior of the sand-cast Mg?10Gd?3Y?0.4Zr alloy was studied by computer aided cooling curve analysis (CA-CCA). With the increase in cooling rate, the nucleation temperature (Tα,N) increases from 634.8 °C to 636.3 °C, the minimum temperature (Tα,Min) decreases from 631.9 °C to 630.7 °C, the nucleation undercooling (ΔTN) increases from 2.9 °C to 5.6 °C, the beginning temperature of the eutectic reaction (Teut,N) increases, the time of the eutectic reaction shortens, solidus temperature decreases from 546.0 °C to 541.4 °C, and solidification temperature range (ΔTS) increases by 6.1 °C. The increased nucleation rate (N&) is supposed to be the main reason for the increased?TN. Increased value (Teut,N?Teut,G) and shortened time of the eutectic reaction cause the change in the volume fraction and morphology of the second phase.
