热处理工艺对挤压态Mg-Zn-Y-Zr镁合金组织性能的影响

Effects of heat treatment on microstructure and mechanical properties of as-extruded Mg–Zn–Y–Zr alloy

摘要:

通过对实验结果进行分析,来探究热处理工艺对挤压态Mg-4.8Zn-1.2Y-0.4Zr镁合金的组织性能的影响规律。研究表明在热处理过程中,挤压态镁合金中的组织发生了明显的变化,T4固溶处理后,虽然合金的晶粒明显长大,但是合金的塑性仍然有显著提升,这主要是因为W相由粗大的鱼骨状分解为细小的颗粒状降低了晶界的阻塞作用；T5热处理后合金中除W相外,还有少量的Mg-Zn相析出,提高了合金的性能。T6热处理后合金中W相几乎全部分解,析出了Mg-Zn和Mg-Y等新相,这些弥散分布的相大大提高了合金的强度和塑性。T6热处理后合金的极限抗拉强度和延伸率分别从挤压态的311MPa、16.89%提高到374MPa、21.97%。最终得到最适合Mg-4.8Zn-1.2Y-0.4Zr合金的热处理方式(500℃× 2h 200℃×48h)。

Abstract:

The effects of the different heat treatment parameters on the microstructure and mechanical property of as-extruded Mg-4.8Zn-1.2Y-0.4Zr magnesium alloy were described based on the experimental results and analysis. The results indicate that the microstructure of alloy changed obviously during heat treatment process. After T4 solution treatment, although the alloy grain has grown obviously, the plastic of alloy has been greatly enhanced. This mainly dues to the massive fish-bone W-phase decomposed into fine granular W phase, which reduces the pinning effect of the grain boundary. After T5 heat treatment, except W-phase, there is a small amount of Mg-Zn phase precipitated in the alloy, which can improve the performance of alloy. After T6 heat treatment, the W-phase has been almost complely decomposed into Mg-Zn and Mg-Y phase. The dispersively distributed phase greatly improves the strength and plasticity, which increases the ultimate tensile strength and elongation from 311MPa and 16.89% in as-extruded alloy to 374MPa and 21.97%. At last the most suitable scheme for heat treatment of Mg-4.8Zn-1.2Y-0.4Zr magnesium alloy is( 500℃×2h 200℃×48h).