热挤压态Mg-10Gd-4Y-0.5Zr合金的时效析出

Aging precipitation of Mg-10Gd-4Y-0.5Zr alloy in hot extrusion state

为提高热挤压态Mg-10Gd-4Y-0.5Zr合金的力学性能,并获得该合金的最佳时效工艺参数,以热挤压态Mg-10Gd-4Y-0.5Zr合金为研究对象,探究了在200℃时效温度下不同时效时间对其硬度和析出相的影响规律。结果表明:在等温时效过程中,随着时效时间的延长,合金的硬度先降低再逐渐增大,在96 h时达到峰值后又逐渐下降;当时效6 h后,晶粒内残存大量位错线,晶粒内生成少量尺寸较小的β′相,此时为欠时效态;随着时效时间的延长,β′相沿着<1010>方向逐渐扩展长大,数量逐渐增多;当时效96 h后,β′相的密度达到最大,并逐渐连接,此时为峰值时效态;当时效120 h后,在晶界处生成尺寸大约为88 nm×237 nm的椭圆状β相,此时为过时效态。

In order to improve the mechanical properties of hot extruded Mg-10Gd-4Y-0.5Zr alloy and obtain the optimal aging process pa-rameters of the alloy,for the hot extruded Mg-10Gd-4Y-0.5Zr alloy,the influences of different aging time on its hardness and precipitated phase at the aging temperature of 200 C were mainly studied.The results show that during the isothermal aging process,with the aging time increases,the hardness of alloy first decreases and then gradually increases,reaching a peak at 96 h,and then gradually decreasing.After aging for 6 h,many dislocation lines remain in the grains,and a small amount of smallerβ'phase is also generated in the grains,which is in an under-aging state.As the aging time increases,β'phase gradually expands and grows along<1010>αdirection,the num-ber gradually increases,and after aging for 96 h,the density ofβ'phase reaches the maximum and gradually connects,which is the peak aging state.After aging for 120 h,the ellipticalβphase with a size of approximately 88 nmx237 nm is generated at the grain boundary,which is the over-aging state.