The mechanical behavior of VCoNi medium-entropy alloys with five different grain sizes at three different temperatures was investigated.The VCoNi alloys with different grain sizes exhibit a traditional strength–ducti...The mechanical behavior of VCoNi medium-entropy alloys with five different grain sizes at three different temperatures was investigated.The VCoNi alloys with different grain sizes exhibit a traditional strength–ductility trade-off at 77 K,194 K and 293 K.Both the yield strength and the uniform elongation of the VCoNi alloys with similar grain size increase with decreasing the deformation temperature from 293 to 77 K.Obvious strain hardening rate recovery characterized by an evident up-turn behavior at stage II is observed in VCoNi alloys with the grain size above 11.1μm.It is found that the extent of the strain hardening rate recovery increases with increasing grain size or decreasing deformation temperature.This may mainly result from the faster increase in the dislocation multiplication rate caused by the decrease in the dislocation mean free path,the decrease in the absorption of dislocations by grain boundaries and the dynamic recovery from the cross-slip with increasing grain size,as well as the suppressed dynamic recovery at cryogenic temperatures.The critical grain sizes for the occurrence of the recovery of strain hardening rate are determined to be around 9.5μm,8.3μm and 3μm for alloys deformed at 293 K,194 K and 77 K,respectively.The basic mechanism for the strain hardening behavior of the VCoNi alloys associated with grain size and deformation temperature is analyzed.展开更多
通通 Formastor 全自动相变仪研究了高强韧性冷作模具钢(LD_1钢即7Cr7MO3V2Si)的加热转变临界点和 Ms 点,研究了加热温度对碳化物溶解及 Ms 点的影响;通过金相及热力学性能测试研究了 LD_1钢淬火温度对奥氏体晶粒度和淬火硬度的影响.淬...通通 Formastor 全自动相变仪研究了高强韧性冷作模具钢(LD_1钢即7Cr7MO3V2Si)的加热转变临界点和 Ms 点,研究了加热温度对碳化物溶解及 Ms 点的影响;通过金相及热力学性能测试研究了 LD_1钢淬火温度对奥氏体晶粒度和淬火硬度的影响.淬火—回火温度对硬度和冲击韧性的影响.以此为判据制定出不同模具的热处理工艺,并进行了实际生产考核.展开更多
基金This work was supported by the National Natural Science Foundation of China(NSFC,Grant No.52071319)the Fundamental Research Project of Shenyang National Laboratory for Materials Science(No.L2019F23).
文摘The mechanical behavior of VCoNi medium-entropy alloys with five different grain sizes at three different temperatures was investigated.The VCoNi alloys with different grain sizes exhibit a traditional strength–ductility trade-off at 77 K,194 K and 293 K.Both the yield strength and the uniform elongation of the VCoNi alloys with similar grain size increase with decreasing the deformation temperature from 293 to 77 K.Obvious strain hardening rate recovery characterized by an evident up-turn behavior at stage II is observed in VCoNi alloys with the grain size above 11.1μm.It is found that the extent of the strain hardening rate recovery increases with increasing grain size or decreasing deformation temperature.This may mainly result from the faster increase in the dislocation multiplication rate caused by the decrease in the dislocation mean free path,the decrease in the absorption of dislocations by grain boundaries and the dynamic recovery from the cross-slip with increasing grain size,as well as the suppressed dynamic recovery at cryogenic temperatures.The critical grain sizes for the occurrence of the recovery of strain hardening rate are determined to be around 9.5μm,8.3μm and 3μm for alloys deformed at 293 K,194 K and 77 K,respectively.The basic mechanism for the strain hardening behavior of the VCoNi alloys associated with grain size and deformation temperature is analyzed.
文摘通通 Formastor 全自动相变仪研究了高强韧性冷作模具钢(LD_1钢即7Cr7MO3V2Si)的加热转变临界点和 Ms 点,研究了加热温度对碳化物溶解及 Ms 点的影响;通过金相及热力学性能测试研究了 LD_1钢淬火温度对奥氏体晶粒度和淬火硬度的影响.淬火—回火温度对硬度和冲击韧性的影响.以此为判据制定出不同模具的热处理工艺,并进行了实际生产考核.
