均匀化处理对6063铝合金挤压型材表面渣粒的影响

采用扫描电镜、金相显微镜和X射线衍射等手段分析不同处理态的合金组织，研究了均匀化处理对6063铝合金型材表面渣粒缺陷的影响，结果表明:铸态合金由富集于晶界呈连续网状的非平衡共晶相与过饱和α-Al固溶体组成；非平衡共晶相由Mg₂Si与β-Al₅FeSi相组成；在均匀化退火过程中发生非平衡共晶相的溶解，针状的β-Al₅FeSi相向颗粒状α-Al₈FeSi相的转变.铸态合金挤出的型材表面有大量渣粒，570 ℃下随均匀化退火处理保温时间的延长，非平衡共晶相逐渐消失，挤压型材表面渣粒数量不断减少. 570 ℃保温6 h退火处理是6063合金铸锭较适宜的均匀化处理工艺. 

Effect of homogenization treatment on the pick-up defect on the surface of extruded 6063 aluminum alloy

The microstructures of as-cast and homogeneous alloys were analyzed by metalloscope, scanning electron microscope and X-ray diffraction. The effect of homogenization treatment on the pick-up defect on the surface of extruded 6063 aluminum alloy were investigated. The results show that as-cast alloy consists of supersaturated α-Al solid solution and non-equilibrium eutectic phase in network structure which uniformly distributes along grain boundaries. The non-equilibrium eutectic is composed of Mg₂Si phase and β-AlFeSi phase. During the process of homogenization treatment, the non-equilibrium eutectic structure broke and dissolved, and the acicular β-AlFeSi phase transformed to spherical α-AFeSi phase. A large number of pick-up defects were observed on the surface of extruded alloy without homogenization treatment. The non-equilibrium eutectic phase disappeared and the number of pick-up defects decreased gradually with the increase of holding time of homogenization treatment at 570 ℃. In conclusion, the proper homogenization treatment of 6063 alloy is at 570 ℃ for 6h.