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研究了挤压Mg-2Zn-x Y(x=0.5,1,2,at%)合金在半固态等温处理过程中的微观组织演变规律。结果表明:3种Mg-2Zn-x Y合金中,挤压Mg-2Zn-1Y合金中α-Mg基体晶粒尺寸最小,挤压Mg-2Zn-2Y合金中出现了大量的孪晶;当半固态等温时间为10 min时,随着等温温度的升高,Mg-2Zn-x Y合金中α-Mg固相晶粒均逐渐趋于球化,且α-Mg固相颗粒逐渐分离,晶界处的液相和晶内液池体积分数均明显增加;随着580℃等温时间的延长(≤30 min),Mg-2Zn-0.5Y合金微观组织演变以Ostwald熟化机制为主,而Mg-2Zn-1Y和Mg-2Zn-2Y合金微观组织演变过程中Ostwald熟化机制和固相颗粒熔化机制同时起主导作用。
The microstructure evolution of extruded Mg-2Zn-xY (x = 0.5,1,2, at%) alloy during semi-solid isothermal treatment was studied. The results show that the grain size of α-Mg matrix in the extruded Mg-2Zn-1Y alloy is the smallest among the three kinds of Mg-2Zn-xY alloys, and a large amount of twins appear in the extruded Mg-2Zn-2Y alloy. When the solid isothermal time is 10 min, the α-Mg grains in Mg-2Zn-xY alloy gradually become nodular with the isothermal temperature increasing, and the α-Mg solid particles are gradually separated, and the grain boundaries The microstructure of Mg-2Zn-0.5Y alloy is dominated by the Ostwald maturation mechanism with the increase of 580 ℃ isothermal time (≤30 min), while Mg-2Zn The mechanisms of Ostwald ripening and solid-phase particle melting also play a leading role in the microstructure evolution of -1Y and Mg-2Zn-2Y alloys.