摘要
The evolution of precipitates and mechanical properties of AZ80A magnesium alloy with aging time was studied by in situ observation with SEM,TEM and tensile testing.The results show that the continuous precipitation(CP)phases near the reaction front(RF)are replaced by the discontinuous precipitation(DP)phases at the early aging stage.In DP regions,the elliptical phases coarsen obviously with the increase of aging time,which results in a slightly slow reduction of the intracrystalline hardness of DP regions.In CP regions,some small plate phases reprecipitate simultaneously with the growth of the initial precipitates,which contributes to a slight increase in the intracrystalline hardness in CP regions at the later aging stage.The aging hardening of DP regions is faster and stronger than that of CP regions.However,the age strengthening of CP regions not only compensates for the overaging softening of DP regions but also improves the strength of the alloy.
通过SEM原位观察、TEM观察和拉伸试验,研究AZ80A镁合金中析出相和力学性能随时效时间的演变规律。结果表明,在时效初期,反应前沿附近由连续析出(CP)产生的析出相逐渐被由不连续析出(DP)产生的析出相所取代。随着时效时间的延长,DP区中的椭圆相明显粗化,导致DP区的晶内硬度缓慢降低;而在CP区,初始析出片状相长大的同时,还析出一些细小的片状相,这使得CP区的晶内硬度在时效后期继续缓慢增加。与CP区相比,DP区具有更快、更强的时效硬化行为。然而,CP区的时效强化不仅可以弥补DP区的过时效软化,而且还能提高合金的强度。
基金
financially supported by the Natural Science Foundation of Hunan Province, China (No. 2018JJ2503)
the Postgraduate Independent Exploration and Innovation Project of Central South University, China (No. 1053320171111)
