铸造Mg-6Zn-(1-2)Y合金热压缩变形行为

Hot Compressive Deformation Behavior of Mg-6Zn-(1-2)Y Casting Alloy

通过常规铸造（金属型）制备了Mg-6.24Zn-1.88Y和Mg-5.96Zn-0.89Y合金.采用Gleeble-3500热模拟试验机在温度为150～350℃、应变速率为0.015～15 s-1条件下,对两种合金的热压缩变形行为进行了研究.结果表明,Mg-6.24Zn-l.88Y合金由α-Mg,I-Mg3YZn6和Mg6.8Y0.35Zn2.81相组成,Mg-5.96Zn-0.89Y合金由α-Mg,I-Mg3YZn6和Mg1 2YZn相组成;增强相多以“共晶组织”形式和杆状分布在α-Mg枝晶间,Mg-6.24Zn-1.88Y合金增强相较多、且组织较细. 150℃变形时孪生起着重要的作用,250℃变形机制由孪生向再结晶逐渐过渡,350℃再结晶是主要的变形机制.在相同形变条件下,含增强相较多、且组织较细的Mg-6.24Zn-1.88Y合金具有较高的应力水平.增强相在热压缩过程中易被破碎、球化,沿流变方向分布.

Mg-6.24Zn-1.88Y and Mg-5.96Zn-0.89Y were prepared by conventional casting （metal mold）.Under the different deformation temperature 150-350 ℃ and strain rate 0.015-15 s-1,thermal simulation testing machine Gleeble-3500 was used to study the hot compression behavior of two alloys.The results show that microstructure in Mg-6.24Zn-l.88Y alloy consists of α-Mg,I-Mg3YZn6 and Mg68Y0.35Zn281,while in Mg-5.96 Zn-0.89Y consists of α-Mg,I-Mg3YZn6 and Mg12YZn; strengthening phases mainly present eutectic morphology and rhabditiform,which might be distributed between α-Mg dendrite; there are more strengthening phases and finer gains in Mg-6.24Zn-1.88Y alloy.Twinning plays an important role in deformation at 150 ℃,and deformation mechanism has transition from twinning to recrystallization at 250 ℃,however,recrystallization becomes the main deformation mechanism at 350 ℃.Mg-6.24Zn-1.88Y alloy,with more strengthening phases and finer gains,show more stress level under the same hot deformation conditions.Strengthening phases were refined,sphericized and distributed along the flow direction during hot compression deformation.