冷却速度对过共晶铝硅合金凝固组织和耐磨性能的影响  

Effects of cooling rate on solidification microstructures and wear resistance of hypereutectic Al-Si alloy

作　　者：赵爱民[1] 毛卫民[1] 甄子胜[1] 姜春梅[2] 钟雪友[1] 

机构地区：[1]北京科技大学铸造研究所,北京100083 [2]北京联合大学应用技术学院,北京100101

出　　处：《中国有色金属学报》2001年第5期827-833,共7页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目 ( 5 97710 11)

摘　　要：试验研究了在不同的冷却速度下凝固的Al 2 0 %Si和Al 30 %Si(质量分数 ,下同 )合金的组织和耐磨性。实验结果表明 ,冷却速度对过共晶铝硅合金的凝固组织和耐磨性能有显著的影响。随着冷却速度的增加 ,Al 2 0 %Si和Al 30 %Si合金的凝固组织组成、初生硅的形貌和尺寸都发生明显的变化 :冷却速度小于 0 .1K/s的炉冷试样和冷却速度小于 1K/s耐火砖型铸造试样的凝固组织由 (α +Si)共晶和初生Si相组成 ,初生Si相呈粗大的片状 ,共晶Si呈针状 ;冷却速度约 10K/s的金属型铸造试样的凝固组织由 (α +Si)共晶、枝晶状α相和初生Si相组成 ,初生Si相为块状或长条状 ,共晶Si呈细小的针状 ,并且凝固组织中出现的枝晶状α相 ;凝固速度为 (10 3 ～10 5)K/s的过喷粉末的凝固组织也是由 (α +Si)共晶、枝晶状α相和初生Si相组成 ,初生Si相为块状。而喷射沉积快速凝固Al 2 0 %Si和Al 30 %Si合金的沉积态组织都是由Si相和α相组成 ,细小的Si相均匀分布在α基体中。随着冷却速度的增加 ,Al 2 0 %Si和Al 30 %Si合金的凝固组织中初生硅的尺寸明显减小 ,磨损机制发生变化 。The microstructures and wear resistance of Al 20%Si and Al 30%(Mass fraction)Si alloys solidified under different cooling rate have been researched. Results of experiments indicates that effects of the cooling rate on solidification microstructures and wear resistance of alloy are significant. When cooling rate increases, the phase constitution of solidification microstructure and the shape and sizes of primary silicon crystal in the microstructure of Al 20%Si and Al 30%Si alloys change obviously. The solidification microstructures both of the specimen solidified in furnace of which the cooling rate is less than 0.1?K/s and the specimen solidified in refractory mold of which the cooling rate is less than 1?K/s are composed of ( α +Si) eutectic and primary Si crystal, and the coarse plate shaped primary Si crystal and needle shaped eutectic Si crystal are inspected in the solidification microstructure. The solidification microstructures of the specimen solidified in metal mold of which the cooling rate is about 10?K/s is composed of ( α +Si) eutectic and primary Si crystal and the dendritic α phase, and the shape of primary Si crystal is plate or block, the eutectic Si crystal is also needle shaped, the dendritic α phase emerged in the metal mold casting specimen. The solidification microstructures of the over spray powder cooled by (10 4～10 6)K/s is also composed of ( α +Si) eutectic and primary Si crystal and the dendritic α phase, and the shape of most of primary Si crystals are fine block. The solidification microstructures both of spray formed Al 20%Si alloy and Al 30%Si alloy are composed of Si crystal and α phase, the fine Si crystals are well distributed in the α phase matrix. With increasing cooling rate, the size of silicon crystal diminished, the wear resistance of Al 20%Si alloy and Al 30%Si alloy increases significantly due to the wear mechanism of alloy changed.

关 键 词：过共晶铝硅合金 冷却速度 凝固组织 耐磨性 

分 类 号：TG292[金属学及工艺—铸造] TG146.21[一般工业技术—材料科学与工程]