热压缩参数对新型粉末高温合金微观组织的影响

Effect of hot deformation parameter on microstructural evolution in a novel P/M superalloy

采用电子背散射衍射(EBSD)方法,研究了某新型粉末高温合金热压缩过程中显微组织演变。结果表明,提高变形温度能够促进动态再结晶(DRX)。随着应变速率的升高,再结晶分数先降低后升高;高变形温度和低应变速率促进了晶粒的生长;变形温度的上升有利于孪晶的形成,但过高温度下界面能降低,孪晶的形成受到抑制。晶界迁移时间抑制孪晶的产生,而高应变速率下储存能的增大导致孪晶含量增大;高变形温度能够增强动态回复(DRV),从而降低几何必须位错(GND)密度。而应变速率的上升由于减少动态回复时间和产生压缩热,使GND密度先上升后下降。

Electron back-scattered diffraction(EBSD)was used to analyze microstructural evolution of a novel P/M superalloy after hot deformation.The results show that increasing deformation temperature can promote dynamic recrystallization(DRX).Meanwhile,the increase of strain rate inhibites the recrystallization first,and then increases the recrystallization fraction.High deformation temperature and low strain rate can promote the grain growth.The increase of deformation temperature is conducive to the formation of twins.However,the reduce of interfacial energy at high deformation temperature will inhibit the formation of twin.Meanwhile,the decrease of migration time first inhibits the formation of twin,and then the increase of storage energy at high strain rate will increase the fraction of twin.The rise of deformation temperature enhances dynamic recovery(DRV),reducing the density of geometrically necessary dislocation(GND).Because of the decrease of DRV time and the generation of compression heat,with the increase of strain rate,GND density first increases and then decreases.