(1. 西華大學(xué) 材料科學(xué)與工程學(xué)院，成都 610039；
2. 四川大學(xué) 材料科學(xué)與工程學(xué)院，成都 610065)
摘 要: 采用自制實驗裝置對Mg-Al-2RE(AE42)合金進行壓入蠕變實驗，利用帶能譜(EDS)的掃描電鏡(SEM)和X射線衍射(XRD)分析合金蠕變前后的組織和成分的演化。結(jié)果表明：隨溫度或應(yīng)力的增加，AE42合金的壓入蠕變速率和第一階段的蠕變量逐漸增加；合金在壓入狀態(tài)下的蠕變應(yīng)力指數(shù)和蠕變激活能的均值分別為3.06和72.4 kJ/mol；壓入條件下AE42合金的穩(wěn)態(tài)蠕變速率由晶界擴散主導(dǎo)的位錯粘滯性滑移控制；鑄態(tài)AE42合金由α-Mg基體、針狀A(yù)l11La3和少量顆粒狀A(yù)l2La組成；固溶處理8 h后，合金中的β-Mg17Al12相溶入α-Mg基體，合金的硬度上升；固溶24 h后，晶粒得到粗化，合金的硬度和抗蠕變性能均下降；固溶處理后再人工時效24 h，晶粒略有細化，但大量β-Mg17Al12相沿晶界不連續(xù)析出，合金的硬度和抗蠕變性能進一步下降。
關(guān)鍵字: AE42合金；壓入蠕變；顯微組織；抗蠕變性能；熱處理
（1. College of Materials Science and Engineering, Xihua University, Chengdu 610039, China;
2. College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China）
Abstract:The indentation creep property of Mg-4Al-2RE (AE42) alloy was analyzed with a special apparatus. The microstructure and compositions of precipitated phases were performed by scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) and X-ray diffractometry (XRD). The results reveal that the steady creep rates and primary indentation deformation of AE42 alloy increase with increasing temperature and stress. The average stress exponent and creep activity energy are 3.06 and 72.4 kJ/mol, respectively. The indentation steady creep rate is controlled by dislocation viscosity slipping led by the grain boundary diffusion. The as-cast AE42 alloy consists of α-Mg matrix, acicular Al11La3 and granular Al2La. The microhardness of AE42 alloy is increased after solution for 8 h as the result of β-Mg17Al12 phase dissolving into α-Mg matrix. But the microhardness and creep resistance of AE42 alloy decrease after solution for 24 h because of the grains coarsening. The microhardness and creep resistance decrease further after 24 h ageing treatment for large number of β-Mg17Al12 phase precipitated discontinuously at the grain boundaries notwithstanding the grains are fined a little.
Key words: AE42 alloy; indentation creep; microstructure; creep resistance; heat treatment
