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利用粉末冶金法,使用TiO2和1B2O3粉末,研究了在Al-TiO2,Al-B2O3和Al-TiO2-B2O3系统中分别形成钛铝金属间化合物、硼铝金属间化合物以及TiB2的原位反应过程.研究结果表明,TiAl3、AlB2和TiB2分别在加热到650℃,750℃和750℃开始形成.X射线衍射分析发现,除了这三个应该出现的平衡相之外,没有探测到其它亚稳相.对不同加热温度下的显微组织观察分析发现,这些增强物在高温反应过程中量的增加都强烈依赖于相的长大,而非相的形核。在Al-TiO2系统中,TiAl3的形成在铝的熔点下开始,显微组织中存在二种形态的TiAl3相;一种是在加热过程中形成的,其边缘在TiO2的进一步还原过程中被部分地消耗;另一种是在冷却过程中由于α-Al析出过量Ti而形成的.在Al-B2O3系统中,AlB2在750℃到 850℃之间形成,其形态与AlB2相同,但宽度较小.在Al-TiO2-B2O3系统中,TiB2在750℃开始形成,细小的TiB2颗粒分布在原始铝颗粒的界面处与α-Al2O3混合在一起,而粗大的TiB2颗粒则分布在α-Al的晶界上.
In-situ reaction of TiAl intermetallic compounds, boron-aluminum intermetallic compounds and TiB2 in Al-TiO2, Al-B2O3 and Al-TiO2-B2O3 systems was investigated by powder metallurgy using TiO2 and 1B2O3 powders respectively. The results show that TiAl3, AlB2 and TiB2 begin to form when they are heated to 650 ℃, 750 ℃ and 750 ℃, respectively.X-ray diffraction analysis shows that no other metastable phase is detected besides the three equilibrium phases that should appear. Microstructural observations at different heating temperatures revealed that the increase in the amount of these reinforcements during high temperature reactions strongly depends on the phase growth rather than the phase nucleation. In the Al-TiO2 system, the formation of TiAl3 begins at the melting point of aluminum and there are two morphologies of TiAl3 phase in the microstructure; one is formed during the heating and the edge is partially modified during the further reduction of TiO2 And the other is due to the precipitation of excess Ti during the cooling of Al-B 2 O. In the Al-B 2 O 3 system, AlB2 forms between 750 ° C. and 850 ° C. and has the same morphology as AlB2 but with a smaller width In the Al-TiO2-B2O3 system, TiB2 begins to form at 750 ℃. The fine TiB2 particles are mixed with α-Al2O3 at the interface of the original aluminum particles while the coarse TiB2 particles are distributed in the α-Al crystal Boundary.