添加钙和转速对旋转容器半固态铸造AZ91镁合金显微组织和凝固参数的影响  

Effect of Ca and rotation speed on microstructure and solidification parameters of AZ91 magnesium alloy produced by semi-solid casting through rotating container process

作　　者：Saeed G.SHABESTARI Ehsan GHANIABADI Saeed G.SHABESTARI;Ehsan GHANIABADI(School of Metallurgy and Materials Engineering,Iran University of Science and Technology,1684613114 Tehran,Iran)

机构地区：[1]School of Metallurgy and Materials Engineering,Iran University of Science and Technology,1684613114 Tehran,Iran

出　　处：《Transactions of Nonferrous Metals Society of China》2023年第2期396-408,共13页中国有色金属学报（英文版）

摘　　要：采用旋转容器半固态工艺(RCP)和添加1%Ca(质量分数)对AZ91镁合金的显微组织进行改性。在半固态加工过程中进行热分析(CA-CCTA),以确定合金的显微组织改性与RCP参数之间的关系。在580~640℃温度条件下,以0、150、180和210 r/min的转速旋转装有熔融AZ91合金的容器。为了确定合金的凝固特性、固相分数和枝晶搭接点(DCP),绘制冷却曲线。结果表明,随着转速的增加,冷却速率显著增加,AZ91和AZ91-1Ca(质量分数,%)的最大凝固范围分别增加15.9和6.4℃。当转速为180r/min时,对浆料施加剪切力可使固相分数最小化并延迟DCP的出现。晶粒尺寸和圆形度等显微组织特征也受到影响。在585℃和180 r/min条件下可得到圆形度为0.72、晶粒尺寸为73.4μm的球状组织。在最佳RCP条件下,向AZ91合金中添加1%Ca可使晶粒的圆形度增加到0.81,晶粒尺寸减小至53.2μm。Microstructure of AZ91 magnesium alloy was modified by using semi-solid rotating container process(RCP)and addition of 1 wt.%Ca.Thermal analysis(CA-CCTA)was performed during semi-solid process in order to determine the relationship between microstructural modification and RCP parameters.The container containing molten AZ91 alloy was rotated by rotation speed of 0,150,180 and 210 r/min at 640-580°C.The cooling curves were plotted to determine the solidification characteristics,solid fraction and dendrite coherency point(DCP).The results indicated that the cooling rate increased with increasing the rotation speed significantly and led to an increase in maximum solidification range of 15.9 and 6.4°C for AZ91 and AZ91-1Ca(wt.%),respectively.Applying shear force to the slurry at 180 r/min minimized the solid fraction and delayed appearance of DCP.It affected the microstructure characteristics such as grain size and circularity factor.The rotation of 180 r/min at 585°C resulted in the globular microstructure with a circularity factor of 0.72 and a grain size of 73.4μm.The addition of 1 wt.%Ca to AZ91 in the optimum condition of RCP increased the circularity factor to 0.81 and reduced the grain size to 53.2μm.

关 键 词：半固态 镁合金 热分析 剪切力 球状组织 

分 类 号：TG146.22[一般工业技术—材料科学与工程]