Influence of multi-cycle cryogenic treatment and tensile temperature on microstructure,mechanical properties and fracture mechanism of as-extruded Mg-10Gd-3Y-0.5Zr magnesium alloy was investigated.The results show that there have no significant changes in tensile properties of the tested alloy after 10 d in liquid nitrogen immersion or 10 cycles of high-low temperature treatment at all test temperatures.The room temperature ultimate tensile strength increases from 398 MPa to 417 MPa after 20 cycles of high-low temperature treatments.Compared with the room temperature,the tested alloys exhibit higher tensile properties at low temperatures.At-196 ℃,the yield strength and ultimate tensile strength of the as-extruded-T5 Mg-10Gd-3Y-0.5Zr alloy are 349 MPa and 506 MPa,respectively,increasing by about 18％ and 27％,respectively.The transgranular cleavage fracture mechanism is observed at room temperature,while at low temperatures both ductile fracture and cleavage fracture behaviors coexist.%研究多循环低温交变(液氮浸泡处理)和拉伸温度对挤压态Mg-10Gd-3Y-0.5Zr镁合金的微观组织、力学性能以及断裂机制的影响.结果表明,Mg-10Gd-3Y-0.5Zr合金经10d液氮浸泡或10个周期高低温交变循环后,合金室温力学性能基本不变;而经过20个周期高低温循环后,合金的室温抗拉强度由398 MPa升高到417 MPa.在-196℃下拉伸时,挤压态Mg-10Gd-3Y-0.5Zr镁合金的屈服强度和抗拉强度均大幅度提高,分别为349MPa和506MPa,分别增长了18％和27％.合金室温断裂机制为穿晶解理断裂,而低温条件下为韧性断裂和解理断裂并存的混合断裂机制.
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