(東莞理工學(xué)院 機械工程學(xué)院，東莞 523808)
摘 要: 在溫度為473~573 K、外加應(yīng)力為30~100 MPa下，對硅酸鋁短纖維增強AZ91D鎂基(Al2O3-SiO2(sf)/AZ91D)復(fù)合材料及AZ91D鎂合金進行拉伸蠕變實驗。通過SEM和TEM檢測方法對其蠕變微觀組織變化和變形規(guī)律進行研究。結(jié)果表明，當(dāng)兩種材料的真應(yīng)力指數(shù)n=3時，蠕變速率受位錯的黏滯性滑移控制；復(fù)合材料的門檻應(yīng)力增大、短纖維有效的承載和傳載作用導(dǎo)致復(fù)合材料的蠕變抗力顯著增大。短纖維表面上的MgO保護層增大了短纖維的承載和傳載作用；短纖維的存在阻礙了復(fù)合材料的蠕變變形，降低了蠕變變形速率，控制著整個蠕變變形過程。
關(guān)鍵字: 鎂基復(fù)合材料；蠕變；載荷傳遞；微觀組織
（School of Mechanical Engineering, Dongguan University of Technology, Dongguan 523808, China）
Abstract:The tensile creep tests were conducted on Al2O3-SiO2(sf)/AZ91D composite and an unreinforced AZ91D matrix alloys in the temperature range of 473-573 K and stress range of 30-100 MPa. By scanning electron microscopy and transmission electron microscopy, the microstructural effects on the creep behavior of the two materials were discussed. The results show at a true stress exponent of n=3 for the two materials, and creep rate is affected by the viscosity slip control of the dislocation. The creep resistance of the reinforced material is shown to be considerably improved compared with that of the matrix alloy. The creep strengthening arises mainly from the increase of threshold stress of the composite and the effective load transfer between plastic flow in the matrix and the fibers. The MgO protective layer on the surface of short fibers can increase carrying and transferring of loads of the short fibers. The presence of short fibers can hinder the creep deformation of the composite, reduce the creep deformation rate, and control the whole creep deformation process.
Key words: magnesium matrix composite; creep; load transfer; microstructure
