超声振动对7055铝合金组织及力学性能的影响  

Effect of ultrasonic vibration on the solidification microstructure and mechanical properties of 7055 aluminum alloy

作　　者：王乐酉[1] 吴文祥[1] 马科[1] 邓桢桢[1] 王家淳[1] 

机构地区：[1]苏州有色金属研究院有限公司,苏州215026

出　　处：《材料科学与工艺》2010年第6期838-842,共5页Materials Science and Technology

基　　金：江苏省自然科学基金资助项目(BK2008560)

摘　　要：为改善7055铝合金的凝固组织,在合金凝固过程中施加超声振动.采用光学显微镜观察和室温压缩试验等手段研究了超声振动对7055铝合金凝固组织及力学性能的影响,并对超声细化机理进行了探讨.结果表明:未施加超声时,7055合金中形成粗大枝晶组织;施加超声振动后,可获得细小均匀的非枝晶组织.由于超声振动的空化和声流效应,凝固前对熔体施加超声,产生大量微泡核心,这些微泡核心保留下来而成为形核核心,使凝固组织得到细化;凝固过程中导入超声,枝晶出现断裂,导致了细小均匀组织的形成.此外,超声振动的7055合金铸锭显示了较好的室温压缩性能,压缩屈服强度、抗压强度及其对应的工程应变分别为165、729.2 MPa和34.8%.To improve the structure of 7055 aluminum, ultrasonic vibration was used during the solidification process. The effect of the ultrasonic vibration on the solidification microstructure and mechanical properties of 7055 aluminum alloy were investigated by means of optical microscopy, and room temperature compressive test, and the mechanisms of grain refinement were also discussed. The results show that the coarse dendrite microstructures are formed in the 7055 aluminum alloy without ultrasonic vibration, however, the microstruc- ture with fine uniform non-dendrite grains can be achieved with ultrasonic vibration. Due to the acoustic cavitation and flows induced by ultrasonic vibration, numerous ultrasonically induced nanobubbles occur before solidification and remain in the molten metal as nucleation centers, which lead to the grain refinement of the so lidification microstructures. The dentrite is broken up by ultrasonic vibrations during the solidification process, which makes the microstructure refined. The 7055 alloy produced with ultrasonic vibration exhibits better mechanical properties at room temperature. The compressive yield strength, ultimate compressive strength and fracture strain are 165 MPa,729. 2MPa and 34. 8 %, respectively.

关 键 词：7055铝合金 超声振动 凝固组织 力学性能 

分 类 号：TG292[金属学及工艺—铸造]