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在4 GPa高压下对Mg_(96.17)Zn_(3.15)Y_(0.5)Zr_(0.18)合金进行600~800℃固溶处理,之后在200℃进行等温时效处理.利用TEM,HRTEM,SEM,XRD等分析方法研究了高压固溶及随后时效处理后合金的显微组织,并测试了4 GPa高压下固溶处理后合金的时效硬化曲线.结果表明,在4 GPa高压下固溶能大幅提高Zn在Mg基体中的溶解度,Zn的溶解度由常压下400℃固溶后的2.11%(质量分数,下同)提高到4 GPa高压下700~800℃固溶后的约6.60%,获得了过饱和a-Mg固溶体.在随后的200℃温时效过程中,高压固溶合金在较短的时间内即可获得较高的近峰值硬度,4 GPa下800℃固溶的合金近峰值时效硬度高达105 HV,比400℃固溶处理合金近峰时效硬度(81 HV)提高了约30%.HRTEM观察表明,4 GPa高压下固溶合金时效沉淀析出相具有很高的析出密度,且析出相中含有粒状准晶I-Mg_3Zn_6Y相.
The Mg_ (96.17) Zn_ (3.15) Y_ (0.5) Zr_ (0.18) alloy was solution treated at 600 ~ 800 ℃ under high pressure of 4 GPa and then isothermally treated at 200 ℃. TEM, HRTEM, SEM and XRD The microstructure of the alloy after high-pressure solution treatment and subsequent aging treatment was studied and the age-hardening curve of the alloy after solution treatment at 4 GPa was tested. The results show that the solid solution treatment at 4 GPa can significantly increase the Zn The solubility of Mg matrix and the solubility of Zn were increased from 2.11% (mass fraction, the same below) at 400 ℃ under atmospheric pressure to about 6.60% after 700 ℃ and 800 ℃ under high pressure at 4 GPa, a-Mg solid solution.In the subsequent 200 ℃ aging process, the high-pressure solid solution alloy can obtain a high near-peak hardness in a short period of time, and the near-peak hardness of the solution alloy at 800 ℃ for 4 GPa reaches 105 HV is about 30% higher than the near-peak hardness (81 HV) of solution treated alloy at 400 ℃ .HRTEM observation shows that the precipitated phase precipitates at high pressure of 4 GPa with high precipitation density, and precipitates contain Granular quasicrystalline I-Mg_3Zn_6Y phase.