【作者】 张修丽； 孙晓慧； 徐红霞； 李德辉；

【Author】 ZHANG Xiu-li~1 SUN Xiao-hui~1 XU Hong-xia~1 LI De-hui~2 (1.Department of physics,Shanghai University of Engineering Science,Shanghai 201620,China;2.Light Alloy Net Forming National Engineering Research Center,Shanghai Jiao tong University,Shanghai 200030,China)

【机构】 上海工程技术大学物理教学部； 上海交通大学轻合金精密成型国家工程研究中心；

【摘要】 研究了 Mg-Zn-Zr 合金在438K 和473K 时效过程中的硬化软化现象。合金在初期(2h 左右)出现了一次明显的时效硬化峰,之后硬度急剧下降；在10h 左右又出现小幅二次硬化现象,随着时效时间的增加,材料不断软化。微观结构分析表明, 初次时效峰是合金中析出了 MgZn5．X 沉淀相及板条状组织所致。随后 MgZn5．X 沉淀相及板条状组织开始溶解减少,合金硬度下降；位错组织的形成是导致合金二次硬化的关键因素。在时效过程中沉淀相的溶解以及晶界宽度的增大导致合金软化。更多还原

【Abstract】 The effect of ageing on the hardening and softening of Mg-Zn-Zr alloys was studied at 438K and 473K.An obvious age hardening in alloys occurs when aging about 2 hours,then the hardness decreases sharply.A second small hardening occurs about 10 hours,and the hardness of alloys decreases with the following ageing.The microstructure investigations by TEM reveal that the first hardening owes to the occurrence of the MgZn5.X precipitate phase and the lathy structure.The sharp fall of the hardness results from the dissolution of MgZn5.X phase and lathy structure.The occurrence and increase of dislocation in alloys is the key reason of second hardening.The dissolution of MgZn5.X phase and the enlargement of the grain boundary result in softening in alloys.更多还原