金属型铸造与半固态流变压铸2024铝合金组织对比  

Comparative Analysis of Microstructure of Rheo-Diecasting and Permanent Mold Casting 2024 Wrought Aluminum Alloy

作　　者：索江龙[1] 李元东[1,2] 李艳磊[1] 何明涛[1] 胡韶华[1] 马颖[1,2] 

机构地区：[1]兰州理工大学甘肃省有色金属新材料省部共建国家重点实验室 [2]兰州理工大学有色金属合金省部共建教育部重点实验室

出　　处：《特种铸造及有色合金》2013年第4期341-347,共7页Special Casting & Nonferrous Alloys

基　　金：国家自然科学基金资助项目(50964010);甘肃省高等学校基本科研业务费资助项目(1201ZTC056)

摘　　要：采用光学显微镜(OM)、扫描电镜(SEM)、X射线衍射仪(XRD),研究了2024变形铝合金在半固态流变压铸过程中的组织特征。结果表明,流变压铸成形的2024变形铝合金的组织主要由球状和类球状的初生α-Al相,与颗粒间不规则的连续网状分布的共晶相θ-CuAl2相及S-CuAl2Mg相组成。二次凝固的过程主要分3个阶段:"脚趾"状和"齿"状初生α2相依附生长,爆发形核产生呈等轴状的初生α3相和共晶反应。共晶组织主要以共生生长方式为主,α-Al相、θ-CuAl2相和S-CuAl2Mg相之间的横向扩散来促使各相的交替生长,形成的层片状共晶组织,主要以"搭桥"方式形成。Microstructural characteristics of the residual liquid phase in semi-solid 2024 wrought aluminum alloy slurry in the rheo-diecasting process was investigated by optical microscope(OM), scanning electron microscope(SEM) and X-ray diffraction(XRD). The results indicate that the microstructure of rheo-diecasted 2024 wrought aluminum alloy is composed of spherical and near-spherical primary α-Al phase, and irregular eutectic θ(CuAl2) and S(CuAl2Mg) phase which is continuously distributed in grain boundary. The secondary solidification process consists of three stages: direct growth of secondary primary (α2) phase from the surface of the primary α-Al phase particles without re-nucleation, independent nucleation of α3 phase from residual liquid and followed by the equiaxed growth, and finally the eutectic reaction. Coupled growth is the main solidification process of eutectic action. The eutectic α-Al attaches to the eutectic θ(CuAl2) phase and S(CuAl2Mg) phase, and grows through the bridge-growth mechanism. The α-Al、θ(CuAl2) phase and S(CuAl2Mg) phase are precipitated alternately after each other, and α-Al+θ(CuAl2)+S(CuAl2Mg) phase will form a laminar eutectic structure.

关 键 词：半固态 2024变形铝合金 流变压铸 自孕育法 

分 类 号：TG292[金属学及工艺—铸造]