摘要
Mg-5.88 Zn-0.53 Cu-0.16 Zr(wt.%)alloy was solidified at 2-6 GPa using high-pressure solidification technology.The microstructure,strengthening mechanism and compressive properties at room temperature were studied using SEM and XRD.The results showed that the microstructure was refined and the secondary dendrite spacing changed from 35μm at atmospheric pressure to 10μm at 6 GPa gradually.Also,Mg(Zn,Cu)2 and Mg Zn Cu eutectic phases were distributed in the shape of network,while under high pressures the second phases(Mg(Zn,Cu)2 and Mg7 Zn3)were mainly granular or strip-like.The solid solubility of Zn and Cu in the matrix built up over increasing solidification pressure and reached 4.12%and 0.32%respectively at 6 GPa.The hardness value was HV 90 and the maximum compression resistance was 430 MPa.Therefore,the grain refinement strengthening,the second phase strengthening and the solid solution strengthening are the principal strengthening mechanisms.
采用高压凝固技术,在2~6 GPa高压下对常规铸造Mg-5.88Zn-0.53Cu-0.16Zr合金进行凝固。利用SEM、EDS和XRD等手段研究高压凝固合金组织特征以及高压凝固实验合金室温压缩性能及其强化机制。结果表明,在高压作用下凝固,实验合金凝固组织得到显著细化,其二次枝晶间距由常压下的35μm逐渐减小到6 GPa下的10μm;在常压下,Mg(Zn)2、Mg7Zn3和Mg Zn Cu共晶相连成网状分布在枝晶间;在高压下,晶间第二相(Mg(Zn,Cu)2和Mg7Zn3相)多颗粒状或条状断续分布枝晶间。Zn和Cu在基体中的固溶度随凝固压力增加而增大,6GPa下高达4.12%和0.32%。6 GPa下,实验合金的硬度高达HV 90,最大压断抗力为430 MPa。细晶强化、第二相强化及固溶强化是其强度提升的主要机制。
基金
Projects(51675092,51775099)supported by the National Natural Science Foundation of China
Projects(E2018501030,E2018501033,E2018501032)supported by the Natural Science Foundation of Hebei Province,China.
作者简介
Corresponding author:Xiao-ping LIN,Tel:+86-13780356091,E-mail:lxping3588@163.com
