制备多物相AlTiC合金的Ti与C熔体反应法

将Ti与C同时加入Al熔体可制备出Ti与C摩尔比分别大于、等于、小于4的3种含不同物相的Al—TiC合金：Al—TiAl3-TiC、Al—TiC、Al-Al4C3-TiC。对纯铝的细化实验表明：不含过量Ti的后两种合金的细化效果相近，Al4C3在Al—TiC合金中的大量出现不会进一步降低合金的细化能力；含TiAl3的第一种合金的细化效率远高于后两者的；TiC物相在基体中以离散颗粒或聚集团形式在Al基体中分布；Al4C3相极脆，易与空气中的水蒸汽反应而分解。分析表明Ti与C在Al熔体中反应生成TiC是通过两条途径同时进行的：熔体中的固体C颗粒与溶解态的Ti直接反应；固体C颗粒和Al反应生成的A4C3与溶解态的Ti发生反应。

Al-Ti-C alloys with different phases prepared through reaction of Ti and C in Al melt

Three kinds of AlTiC alloys with the mole ratio of Ti and C exceeding, equal to or below the stoichiometric value in TiC, i.e. Al-TiAl_3-TiC, Al-TiC, and Al-Al_4C_3-TiC alloys, can be readily produced by a new method involving the simultaneous addition of Ti and C into Al melt. The latter two kinds of alloys have similar refinement efficiencies on pure Al despite of the presence of large amount of Al_4C_3 phase in Al-Al_4C_3-TiC, but their efficiencies are much lower than that of the first one due to the absence of excess Ti beyond the combined in TiC in the matrix, suggesting some significant role of excess Ti in the refinement. TiC phase in the alloys exists in the form of discrete particle or small clusters consisting of several discrete particles, which are homogeneously distributed in the matrix. Large agglomerates of TiC particles along grain boundaries were also observed. Al_4C_3 phase in Al 8Ti3.5C is brittle and easy to react with moisture in the air. Analysis shows that formation of TiC is accomplished through the simultaneous reaction of Ti dissolved in the Al melt with either solid carbon particle or Al_4C_3 phase.