挤压变形Al-4Cu-0.15Zr-0.15Sc合金的显微组织与拉伸性能

Microstructure and tensile properties of extruded Al-4Cu-0.15Zr-0.15Sc aluminum alloy

对经过固溶+单级时效(T6)处理、固溶+双级时效(T7X)处理及固溶+回归再时效(RRA)处理的挤压变形Al-4Cu-0.15Zr-0.15Sc合金进行了室温拉伸性能测试,并利用透射电子显微镜(TEM)、扫描电子显微镜(SEM)对不同处理状态的挤压变形Al-4Cu-0.15Zr-0.15Sc合金的显微组织、拉伸断口形貌等进行了表征。结果表明,经过RRA处理的合金的析出相尺寸最小,弥散程度最大;对于挤压变形Al-4Cu-0.15Zr-0.15Sc合金而言,适宜的热处理工艺为500℃×4 h固溶+120℃×24 h低温预时效+180℃×1 h高温短时回归+120℃×24 h低温终时效,经此工艺处理的合金的抗拉强度、屈服强度和断后伸长率分别为370.36 MPa、285.42 MPa和10.81%;不同加工处理状态的挤压变形Al-4Cu-0.15Zr-0.15Sc合金的拉伸断口表面均存在韧窝和撕裂棱,说明合金在室温拉伸加载条件下均发生韧性断裂。

The tensile tests were performed for the extruded Al-4Cu-0. 15Zr-0. 15 Sc alloy subjected to the solid solution plus aging( T6)treatment,solid solution plus double aging( T7X) treatment and solid solution plus retrogression and reaging( RRA) treatment. The microstructure and fracture surface morphology of the extruded Al-4Cu-0. 15Zr-0. 15 Sc alloys with different treated states were characterized with transmission electron microscopy( TEM) and scanning electron microscopy( SEM). The results show that the size of precipitates is the finest for the extruded Al-4Cu-0. 15Zr-0. 15 Sc alloy subjected by the RRA treatment,the dispersion degree of precipitates is the largest,and the volume fraction of the precipitate is the highest. The suitable heat treatment technology for the extruded Al-4Cu-0. 15Zr-0. 15 Sc alloy is the solid solution treatment at 500 ℃ for 4 h,low temperature presaging at 120 ℃ for 24 h,high temperature regression at 180 ℃ for 1 h plus low temperature aging at 120 ℃ for 24 h. After the above-mentioned treatment,the ultimate tensile strength,yield strength and elongation of the alloy are 370. 36 MPa,285. 42 MPa and 10. 81%,respectively. In addition,the ductile fracture occurs in the tensile loading condition for the extruded Al-4Cu-0. 15Zr-0. 15 Sc alloys with different processed and treated states.