摘要
The effect of Ti addition on microstructure and mechanical properties of Zn-22Al eutectoid alloy with 0.15 wt%Ti was investigated.It was observed that the presence of Ti changes the morphology of n phase in the alloy.Addition of Ti to Zn-Al alloy caused the formation of Ti(Zn,Al)_(3);phase.Before applying equal channel angular pressing(ECAP),two times of homogenization treatment were conducted on the alloy.After secondary homogenization,the microstructure consisted of a homogeneous and fine mixture ofαand n phases and the as-cast lamellar structure removed.After homogenization,ECAP was carried out on Ti-containing Zn-22Al alloy.The fraction of high angle grain boundaries increased with increasing the number of ECAP passes.The average grain size reduced from 930 nm after secondary homogenization to 380 nm after 8 passes of ECAP.The texture of the alloy also changed by applying ECAP.Maximum elongation to failure of the homogenized alloy was 135%at a strain rate of 10^(-5)s^(-1)which enhanced to a maximum of 405%at a strain rate of 10^(-3)s^(-1)after 8 passes of ECAP.It was also observed that by conducting ECAP and increasing the number of passes the hardness decreases,which indicates work-softening behavior due to dynamic recovery/recrystallization.
研究了添加Ti对含0.15 wt%Ti的Zn-22Al共析合金显微组织和力学性能的影响。结果表明,Ti改变了合金中η相的形貌。在Zn-Al合金中加入Ti可以形成Ti(Zn,Al)_(3)相。在等径角挤压前,对合金进行两次均匀化处理。二次均匀化后,组织为α相和η相的不均匀细小混合物,并去除了铸态层状组织。均匀化后,对含Ti的Zn-22Al合金进行等径角挤压。随着道次的增加,大角度晶界的比例提高。经过8次等径角挤压后,晶粒平均尺寸由二次均匀化后的930 nm减小到380 nm。等径角挤压后,合金的织构也发生了变化。在应变速率为10~(-5)s^(-1)时,均匀化合金的最大伸长率为135%,经8次等径角挤压后,在应变速率为10^(-3)s^(-1)时,最大伸长率为405%。还观察到,通过等径角挤压和增加道次,合金的硬度降低,这表明出现了动态恢复/重结晶并导致了加工软化。
