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采用原位反应制得了纯净的Ti B2/7075复合材料。研究表明,随着Ti B2颗粒含量增加,树枝状的7075铝合金逐渐转化为细小的蔷薇状,Ti B2颗粒含量增加到4.5%(质量分数)时α-Al晶粒尺寸达到最小,之后又重新转化为粗大的树枝晶。3%Ti B2/7075合金的晶界处Ti B2颗粒尺寸一般在900~1400 nm,Ti B2颗粒大致呈六边形或四方形。当颗粒含量达到9%时,大尺寸的Ti B2颗粒分布在晶界处,晶界附近的晶核内弥散分布着大量细小的Ti B2颗粒,尺寸在100~400 nm左右,形状为不规则的多边形,细小的Ti B2颗粒容易在固/液界面被捕获,产生颗粒推移效应。在720℃保温发现,3%,6%,9%Ti B2/7075复合材料中Ti B2颗粒的平均沉降速率分别为2.308×10-6,1.146×10-6,0.371×10-6m·s-1,原位颗粒增多,抗沉降能力增强。
The in-situ reaction was used to prepare pure Ti B2 / 7075 composite. The results show that as the content of Ti B2 particles increases, the dendritic 7075 aluminum alloy gradually transforms into a small rosette. When the content of Ti B2 particles increases to 4.5% (mass fraction), the α-Al grain size reaches the minimum, Transform into coarse dendrites. The grain size of Ti B2 at the grain boundary of 3% Ti B2 / 7075 alloy is generally 900-1400 nm, and TiB2 particles are roughly hexagonal or tetragonal. When the content of the particles reaches 9%, large size TiB2 particles are distributed in the grain boundaries, and a large number of fine TiB2 particles are distributed dispersedly in the nuclei near the grain boundaries with sizes of about 100-400 nm with irregular shapes Polygonal, fine Ti B2 particles are easily trapped at the solid / liquid interface, creating a particle slip effect. The average deposition rates of Ti B2 particles in 3%, 6% and 9% Ti B2 / 7075 composites were found to be 2.308 × 10-6,1.146 × 10-6 and 0.371 × 10-6m · s- 1, in situ particles increased anti-settling ability.