铁铝原子在金属间化合物形成中的扩散

Fe and Al Atoms Diffusion in Intermetallic Formation

采用铁铝扩散偶，研究铁铝原子在化合反应中的扩散和金属间化合物的形成机理．扩散偶在铁铝低共熔反应温度上下进行热处理．结果表明，扩散偶在低于共熔反应温度处理时，在扩散偶铁－铝界面铁的一侧，通过铝原子的扩散，形成了富铝相金属间化合物ＦｅＡｌ３；而在高于共熔反应温度处理时，则在铁－铝界面上，通过铁、铝原子的互扩散形成了金属间化合物Ｆｅ２Ａｌ５，并随时间向两旁生长．两种化合物均为多孔体．研究发现铁、铝原子的扩散首先沿晶界扩散，在晶界上发生反应并生成化合物，然后由晶界向晶内扩散并进行化合反应．研究测得铁铝的互扩散系数和扩散活化能．本文讨论了金属间化合物的形成机理．

The mechanism of iron and aluminum intermetallics formation during the reactive sintering of the two mixing powders has been studied by investigating iron aluminum diffusion couples. These two materials are treated both below and above the lowest eutectic temperatures of Fe Al system. It is found that at 600 ℃ below the eutectic temperature an Al rich intermetallic FeAl 3 is formed in iron adjacent to the interface of iron and aluminum by aluminum diffusion into iron, while above 700℃(above the eutectic temperature) an intermetallic Fe 2Al 5 is formed in both iron and aluminum on the two sides of the initial interface. Accompanied with the Fe Al reaction during the treatment under both conditions is the diffusion of iron and aluminum atoms. The reactive sintering of FeAl intermetallics is a process—diffusion and chemical reaction. The diffusion coefficients of iron and aluminum and the activation energies are obtained. The mechanism of the intermetallic formation in the couples is also discussed.