Mg-5Sn-1Zn-0.5Zr合金的显微组织与时效硬化行为

Microstructure and ageing hardening behavior of Mg-5Sn-1Zn-0.5Zr alloy

研究了Mg-5Sn-1Zn-0.5Zr(SZK510)合金经固溶处理(480℃×10h)和175、200、225℃,1～100h时效处理后的时效硬化行为和显微组织特征,并推导出该合金的时效动力学方程。结果表明,固溶时效处理后显微组织由α-Mg和Mg2Sn,以及少量的MgZn相和α-Zr组成;试验合金具有明显的时效硬化特征:在3个不同的时效温度下,硬化曲线都呈抛物线形状,但在175℃时效时,曲线出现两个峰值,并且在保温时间为3.98h有最大的显微硬度值;试验合金的时效动力学方程符合f=1-exp(-ktm)关系,随着时效温度提高,k值减小m值增大。

The aging hardening behavior and microstructure of Mg-5Sn-1Zn-0. 5Zr（SZK510） alloy solutionized at 480 ℃ for 10 h and aged at 175 ℃ ,200 ℃ and 225 ℃ for 1 - 100 h were studied,and the aging dynamie equations were deduced. The results indicate that microstructure of the alloy at T6 state consists of α-Mg, Mg2 Sn, a few MgZn and α-Zr phases. A strong age-hardening characteristic is found in aging hardening curves of the alloy. The parabola characteristic are observed in the three aging temperature vs microhardness curves. When aged at 175 ℃, however,the aging curve has two peak values,and the maximum hardness value is gained at 3. 98 h. The aging dynamic equation of the alloy can be expressed by JEM equation f= 1 -exp（ -kt^m）, and the k value decreases and m value increases when the aging temperature increases.