超声滚压处理7B85合金的显微组织和力学性能

采用不同压下量（0、0.1、0.2、0.3、0.4 mm）对7B85合金进行超声滚压处理,利用光学显微镜、表面粗糙度测量仪、显微维氏硬度计、拉伸实验、扫描电镜、X射线衍射和电子背散射衍射对经过超声滚压处理的7B85合金的微观组织和力学性能进行研究。结果表明,当下压量为0.2 mm时,超声表面滚压处理后7B85合金的表面粗糙度、显微硬度以及抗拉强度达到较优值。滚压处理后合金的断口形貌呈现出大量较深的韧窝,其主要以韧性断裂形式为主。同时,超声表面滚压处理后合金中大部分η析出相溶解到铝基体中,其表层晶粒的平均晶粒尺寸约为（25.22 ± 6.46）nm。滚压后合金力学性能的提高主要归因于合金表面细晶强化和应力强化的共同作用。 

Microstructure and mechanical properties of 7B85 alloy ultrasonic rolling treated 7B85 alloy

The 7B85 alloy was treated by ultrasonic rolling treatment (USRT) with different preloading depth (0, 0.1, 0.2, 0.3 and 0.4 mm). The microstructure and mechanical properties of 7B85 alloy treated by ultrasonic rolling were investigated by optical microscope, surface roughness tester, micro Vickers hardness test, tensile test, scanning electron microscope, X-ray diffraction and electron back scattering diffraction. The results show that the surface roughness, microhardness and tensile strength of 7B85 alloy treated by ultrasonic surface rolling reached the optimal value, when the preloading depth was 0.2 mm. The fracture morphology of the 7B85 alloy showed a large number of deep dimples, which were mainly in the form of ductile fracture. Meanwhile, most of the η precipitates in the 7B85 alloy are dissolved into the aluminum matrix after USRT, and the average grain size of the alloy surface is about (25.22 ± 6.46) nm. The improvement of the mechanical properties of the 7B85 alloy after USRT is mainly attributed to the joint action of fine grain strengthening and stress strengthening on the alloy surface.