熔体反应内生Al基复合材料的制备和凝固组织控制

PROCESSING OF IN SITU ALUMINUM-MATRIX COMPOSITES AND CONTROLLING OF THE SOLIDIFICATION MICROSTRUCTURES

采用一种新型的金属基复合材料制备工艺──熔体反应法．制备了二种内生颗粒增强Al基复合材料:一种为Al／TiAl3，另一种为分别采用混合盐体系和氧化物体系制备的Al-4.5Cu／TiB2Al／TiAl3复合材料中的TiAl3随熔体反应时间增加和反应温度的升高，由细小的颗粒（＜3μm）长成粗大的短棒状组织，混合盐体系制备的Al-4．5Cu／TiB2复合材料中的TiB2颗粒细小（＜2μm），但被熔盐包覆，削弱了其对基体的增强效果．氧化物体系制备的Al-4．5Cu／TiB2复合材料中的TiB2颗粒的平均尺寸为0．93μm，TiB2颗粒表面洁净，与基体结合好，该复合材料的力学性能优越，σb＝416.7MPa，σ0.2＝316．9MPa，δ＝3．3％，HV153。

A novel in situ reaction process - reaction technique in melt was developed. The two kinds of in situ particle reinforced composites were fabricated by it. They are Al/TiAl3 and Al-4.5Cu/TiB2.The Al-4.5Cu/TiB2 composites were made from K2TiF6-KBF4-Na3AlF6-Al-4.5Cu system and TiO2 -H3BO3-Na3AlF6-Al-4.5Cu system, respectively. TiAl3 particle in Al/TiAl3 composite is influenced by reaction temperature and time, its size and shape vary from small particle shape (<3 μm) to short coarse bar shape. TiB2 particle in Al-4.5Cu/TiB2 composite is very small (<2 μm) and covered with molten salts, which reduces the reinforced effect of the matrix. TiB2 particle in Al-4.5Cu/TiB2 composite is about 0.93 pm in size and combines with the matrix of the composite well. The interface between TiB2 particle and Al-4.5Cu mains is clean. The properties of Al-4.5Cu/TiB2 composite are excellent: σb=416.7 MPa,σ0.2=316.9 MPa, δ=3.3%, HV 153.