Samples of directionally solidified Mg-9Zn-2Y alloys have been obtained using vacuum induced directional solidification equipment. The metallographic structures and mechanical properties at room and high temperatures of the directionally solidified alloys have been investigated and compared with those of conventional casting alloys. The structures have consisted of columnar crystals with a specific orientation, and the parallel phases near the grain boundaries and inside the grains have quasi-crystals of I-Mg₃Zn₆Y. At room temperature, the maximum compressive resistance and section expansion ratio of the directionally solidified alloys have been 54 and 31% higher, respectively, than those of the conventional casting alloys. The peak stress of the directionally solidified alloys has found 238 MPa, which is 57% higher than that of the conventional casting alloys (152 MPa) at 200 °C with a strain rate of 0.1 s^-1. In addition, the peak stress was 140 MPa at 300 °C with a strain rate of 0.1s^-1, while it was only 84 MPa for the conventional casting alloys. Therefore, the directionally solidified alloys has higher strength and plasticity at room temperature and improved mechanical properties at a high temperature.

中文翻译：

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Mg-9Zn-2Y定向凝固合金的组织和力学性能

使用真空诱导定向凝固设备获得了定向凝固的Mg-9Zn-2Y合金样品。已经研究了定向凝固合金在室温和高温下的金相组织和力学性能，并将其与常规铸造合金进行了比较。该结构由具有特定取向的柱状晶体组成，并且靠近晶界和晶粒内部的平行相具有I-Mg ₃ Zn ₆准晶体。Y.在室温下，定向凝固合金的最大抗压强度和截面膨胀率分别比常规铸造合金高54和31％。定向凝固合金的峰值应力为238 MPa，比200℃，应变率为0.1 s ^-1的常规铸造合金（152 MPa）的峰值应力高57％。另外，在300℃下的峰值应力为140MPa ，应变率为0.1s ^-1，而常规铸造合金的峰值应力仅为84MPa。因此，定向凝固的合金在室温下具有较高的强度和可塑性，并且在高温下具有改善的机械性能。