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采用粉末法,在不同Y含量的TiNi形状记忆合金基体上制备了650℃渗铝涂层,并对Y影响涂层的形成以及涂层在700℃恒温氧化性能进行了研究。结果表明:渗铝涂层由外层TiAl_3和内层NiAl_3构成,涂层的生长主要由Al的内扩散控制。当Y含量低于1at%时,稀土元素Y的添加促进TiAl_3外层的生长,抑制NiAl_3内层的生长。恒温氧化实验表明:添加0.5at%Y能明显降低渗铝涂层的氧化速度,但添加1 at%Y和5 at%Y却加速涂层的氧化。并对Y影响涂层的形成以及恒温氧化性能进行了分析。
A 650 ℃ aluminized coating was prepared on a TiNi shape memory alloy substrate with different Y content by powder method. The formation of Y-influenced coating and the thermostatic oxidation of the coating at 700 ℃ were studied. The results show that the aluminized coating consists of the outer TiAl_3 and the inner NiAl_3, and the growth of the coating is mainly controlled by the inner diffusion of Al. When the Y content is less than 1at%, the addition of rare earth element Y promotes the growth of the outer layer of TiAl_3 and inhibits the growth of the inner layer of NiAl_3. The experiments of constant temperature oxidation showed that the addition of 0.5at% Y significantly reduced the oxidation rate of the aluminized coating, but the addition of 1 at% Y and 5 at% Y accelerated the oxidation of the coating. The influence of Y on the formation of coatings and the oxidation behavior at constant temperature were analyzed.