【摘要】：采用掃描電鏡,X射線衍射儀以及高溫蠕變試驗機等試驗手段研究了Y含量對Mg-5.5Zn重力鑄造鎂合金抗蠕變性能和應(yīng)力指數(shù)的影響.結(jié)果表明:隨著Y含量的增加,Mg-5.5Zn合金中依次出現(xiàn)了Mg7Zn3,Mg3Zn6Y(I-相)和Mg3Zn3Y2(W-相)3種不同類型的強化相,而合金中第二相種類、體積分?jǐn)?shù)發(fā)生變化,導(dǎo)致抗蠕變性不斷提高.在同樣的蠕變條件下,高熔點稀土相比低熔點Mg7Zn3相更能降低合金的穩(wěn)態(tài)蠕變速率.Mg-5.5Zn-(0.7,1.5,3.5)Y(wt%)3種合金在175℃/50~60 MPa下的應(yīng)力指數(shù)n分別為5.2,3.2和2.2,在200℃/50~60 MPa下應(yīng)力指數(shù)n分別為11.0,3.8和2.9.Mg-5.5Zn-0.7Y合金在175℃/55 MPa和200℃/55 MPa條件下的蠕變機制分別為位錯攀移和Power-Law方程失效.Mg-5.5Zn-(1.5,3.5)Y兩種合金在175~200℃/50~60 MPa范圍下的蠕變機制是位錯粘滯運動.
[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，

本文編號：2408157