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利用电子拉伸试验机对挤压态Mg-7.98Li合金在不同加载速率下进行拉伸试验,并对拉伸断口进行扫描分析,探讨加载速率对该合金拉伸性能和断裂机制的影响。结果表明,在0.015~15 mm/min的加载速率范围内,随加载速率升高,Mg-7.98Li合金的屈服强度和抗拉强度增加,伸长率和断面收缩率明显降低,该合金产生了显著的应变率强化效应;合金断裂特征表现为韧性断裂。随加载速率升高,其微观断裂机制由微孔聚合剪切断裂向微孔聚合剪切与准解理混合型断裂转变,断口表现出一定的脆化倾向。
Tensile tests were carried out on the Mg-7.98Li alloy at different loading rates using an electronic tensile tester. The tensile fracture was analyzed by scanning electron microscope (SEM) to investigate the effect of loading rate on the tensile properties and fracture mechanism of the alloy. The results show that the yield strength and tensile strength of Mg-7.98Li alloy increase with the increase of loading rate at 0.015-15 mm / min loading rate, and the elongation and reduction of area decrease obviously. Significant strain rate strengthening effect; alloy fracture characteristics of ductile fracture. With the increase of loading rate, the microscopic fracture mechanism changes from microporous polymeric shear fracture to microporous polymeric shear and quasi-cleavage mixed fracture, and fracture shows a tendency of embrittlement.