挤压温度对Mg-9Gd-4Y-0.6Zr合金组织与力学性能的影响

Influence of extrusion temperature on microstructures and mechanical properties of Mg-9Gd-4Y-0.6Zr alloy

为提高Mg-9Gd-4Y-0.6Zr合金的强度,研究了不同温度下的挤压组织对合金力学性能的影响。结果表明,随着挤压温度从500℃降低到400℃,其晶粒度也从126μm细化到7.4μm,抗拉强度和延伸率分别从200.1MPa和2.93%提高到312.4 MPa和5.6%。通过力学性能和晶粒尺寸之间的关系计算出该合金的Hall-Petch常数Ky为327.6 MPa.μm1/2,明显高于纯镁及常规镁合金的Ky。大量稀土元素的固溶及其第二相粒子对晶界和位错运动的阻碍作用是合金Ky值较高的主要原因。

The influence of different extrusion temperatures on the microstructures and mechanical properties of Mg-9Gd-4Y-0.6Zr alloy was investigated. It is found that when the extrusion temperature descends from 500 ℃ to 400℃, the grain size drops from 126μm to 7. 4μm, the tensile strength and elongation increase from 200.1 MPa and 2.93% to 312.4 MPa and 5.6%, respectively. The Hall-Petch constant （Ky = 327.6 MPa · μm^1/2） calculated by the Hall-Petch equation for the alloy is markedly higher than that of pure magnesium and conventional magnesium alloys, which is caused by a great deal of dissolved rare-earths and their second-phase particles by which motions of grain boundaries and dislocations are effectively impeded.