Y对高锌镁合金的拉伸蠕变行为的影响

发布时间：2019-01-12 20:28

【摘要】：采用扫描电镜,X射线衍射仪以及高温蠕变试验机等试验手段研究了Y含量对Mg-5.5Zn重力铸造镁合金抗蠕变性能和应力指数的影响.结果表明:随着Y含量的增加,Mg-5.5Zn合金中依次出现了Mg7Zn3,Mg3Zn6Y(I-相)和Mg3Zn3Y2(W-相)3种不同类型的强化相,而合金中第二相种类、体积分数发生变化,导致抗蠕变性不断提高.在同样的蠕变条件下,高熔点稀土相比低熔点Mg7Zn3相更能降低合金的稳态蠕变速率.Mg-5.5Zn-(0.7,1.5,3.5)Y(wt%)3种合金在175℃/50~60 MPa下的应力指数n分别为5.2,3.2和2.2,在200℃/50~60 MPa下应力指数n分别为11.0,3.8和2.9.Mg-5.5Zn-0.7Y合金在175℃/55 MPa和200℃/55 MPa条件下的蠕变机制分别为位错攀移和Power-Law方程失效.Mg-5.5Zn-(1.5,3.5)Y两种合金在175~200℃/50~60 MPa范围下的蠕变机制是位错粘滞运动.
[Abstract]:The effects of Y content on the creep resistance and stress index of Mg-5.5Zn gravity casting magnesium alloy were studied by means of scanning electron microscope, X-ray diffractometer and high temperature creep tester. The results show that with the increase of Y content, three different types of strengthening phases Mg7Zn3,Mg3Zn6Y (I- phase) and Mg3Zn3Y2 (W- phase) appear in Mg-5.5Zn alloy, while the volume fraction of the second phase in the alloy changes. The creep resistance is improved continuously. Under the same creep conditions, Compared with low melting point Mg7Zn3 phase, high melting point rare earth can decrease the steady state creep rate of the alloy. The stress exponents n of Mg-5.5Zn- (0.7U 1.53.5) Y (wt%) for three alloys at 175 鈩，

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