的組織形成機(jī)制
( 1. 哈爾濱工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院， 哈爾濱 150001；
2. 香港城市大學(xué) 物理及材料科學(xué)系，香港)
摘 要: 采用B或B2O3、 TiO2和Al粉反應(yīng)熱壓制備了原位 (Al2O3+TiB2+Al3Ti)/Al復(fù)合材料，采用光學(xué)顯微鏡、 掃描電鏡和透射電鏡分析了原位復(fù)合材料的顯微組織。 熱壓狀態(tài)下， 反應(yīng)生成相Al3Ti呈大塊不規(guī)則形狀， 尺寸約幾十微米； Al2O3和TiB2為細(xì)小彌散質(zhì)點(diǎn)， TEM分析發(fā)現(xiàn)TiB2顆粒呈六邊形， 而Al2O3顆粒呈等軸狀。在以Al粉、 TiO2粉和B粉為原料制備的復(fù)合材料中， 除反應(yīng)生成了大塊的Al3Ti相外, 還有細(xì)小針狀A(yù)l3Ti相沉淀析出， 且呈彌散分布。熱擠壓后大塊的Al3Ti被破碎成細(xì)小彌散質(zhì)點(diǎn)。 Al2O3在TiO2和B2O3粉末表面生成； TiB2在B或B2O3粉表面形成， 因而均呈彌散分布，且尺寸細(xì)小。 自TiO2中還原出的Ti溶入液態(tài)Al中形成Al3Ti時(shí)， Ti可在液態(tài)Al中長(zhǎng)距離擴(kuò)散， 因而Al3Ti呈大塊不規(guī)則狀。
關(guān)鍵字: 反應(yīng)熱壓； Al基復(fù)合材料； Al2O3; TiB2; Al3Ti; 顯微組織
composites fabricated by reaction hot pressing
（ 1. School of Materials Science and Engineering,
Harbin Institute of Technology, Harbin 150001, China;
2. Department of Physics and Material Science,
City University of Hong Kong, Kowloon, Hong Kong, China）
Abstract: Two (Al2O3+TiB2+Al3Ti)/Al composites were made from Al-B2O3-TiO2 and Al-B-TiO2 raw powders by hot pressing. The microstructure of the two composites was analyzed by OM, SEM and TEM. The results show that coarse Al3Ti blocks with size of several tens of micrometers are formed during hot pressing, and the fine equiaxed Al2O3 and hexagon TiB2 particulates are formed simultaneously. On the other hand, there are fine Al3Ti precipitates in the composite fabricated from Al, B and TiO2 powders. After extrusion, the coarse Al3Ti blocks are broken into small pieces. Al2O3 particles are formed on the surface of TiO2 or B2O3 powder, TiB2 particles are formed on B or B2O3 powders, and they are fine and dispersively distributed. The formation of coarse Al3Ti block is resulted from long-distance diffusion of Ti in liquid Al.
Key words: hot pressing; Al matrix composite; Al2O3; TiB2; Al3Ti; microstructure
