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利用硬度测量和X射线衍射分析,研究了Mg-5%Zn合金的时效硬化过程.指出合金在165℃时效过程中出现两个硬度峰,反映合金内发生了相应的结构变化. 对淬火合金的X射线研究表明,Mg基体中出现平行于(0001)和{1010}面的片状Zn原子富集区.在165℃时效初期,过饱和固溶体合金中桥出细微的二维及三维的亚稳定过渡相β′_1及一维杆状过渡相β′_2.β′_2存在时间很短,β′_2继续生核成长.时效100h后,稳定沉淀相β开始析出,并与β′_2共存.在190℃的时效过程中只出现一个硬度峰,相应于合金中同时出现β′_2及β析出相.测定了β′_1和β′_2过渡相的结构参数及其与母相的取向关系. β′_2的热稳定性相当高,能在250℃长时间存在,说明Mn-Zn系统的时效合金有可能在较高温度下使用.
The age hardening process of Mg-5% Zn alloy was studied by means of hardness measurement and X-ray diffraction analysis. It is pointed out that there are two hardness peaks during aging at 165 ℃, which reflect the corresponding structural changes in the alloy. X-ray studies have shown that there are sheet-like Zn-rich regions parallel to the (0001) and {1010} planes in the Mg matrix.At the beginning of aging at 165 ℃, the subtle two- and three-dimensional metastable bridges in the supersaturated solid solution alloy The transition phase β’_1 and the one-dimensional rod-like transition phase β’_2.β’_2 exist for a short time, β’_2 continue to nucleate and grow.After 100h aging, stable precipitation phase β begins to precipitate and coexists with β’_2. At 190 ℃, only one hardness peak appeared in the aging process, which corresponded to the simultaneous presence of β’_2 and β precipitates in the alloy. The structural parameters of the β’1 and β’2 transition phases and the orientation relationship with the parent phase were determined. The thermal stability of β’_2 is quite high and can exist at 250 ℃ for a long time, indicating that the aging alloy of Mn-Zn system may be used at higher temperature.