离心铸造 Al-Si-Ti 合金梯度功能材料的摩擦学特性

Tribological Properties of Centrifugally Cast Al-Si-Ti Alloy as Functional Gradient Material

采用离心铸造工艺使Ａｌ－Ｓｉ－Ｔｉ合金在凝固过程中析出的富Ｔｉ相（Ｓｉ２Ｔｉ型和Ａｌ３Ｔｉ型）在合金表层聚集而制得梯度功能材料．测定了这种材料的硬度并对其摩擦学性能进行了试验研究．结果表明：在２０～２５０℃温度范围内，材料表层（复合层）的硬度比内部基体的高，在以氧化和粘着磨损为主的前期磨损过程中，由于富Ｔｉ相聚集的复合层硬度高，耐热性和抗氧化性优良，复合层的磨损率远比内部基体的低；在进入稳定磨损阶段后，氧化磨损和粘着磨损都明显降低，由于富Ｔｉ相的存在增加了萌生裂纹的相界面，相邻裂纹容易连通，疲劳磨损倾向增大，复合层的磨损率与内部基体的接近．

The Al-Si-Ti alloy is used for making functionally gradient materials by centrifugal casting, which can deposite enriched Ti phases(types of Si 2Ti and Al 3Ti) during the solidifying process in the alloy surface layer. The hardness and tribological properties of the material were tested. The results showed that the hardness of the surface layer (composite layer) of the materials is higher than that of the inner matrix structure under 20￣250 ℃ range. At the initial stage of oxidation and adhesion wear, the wear rate of the composite layer consisting of enriched Ti phases is remarkably lower than that of matrix because of its high hardness, good heat resistance and anti oxidation. In the stable stage of wear process, oxidation and adhesion wear decreased obviously, but the fatigue wear increased and the wear rate of the composite layer is close to that of the matrix, because the enriched Ti phases increased the phase interface producing cracks and the neighboring cracks linked up easily. This kind of functionally gradient materials is suitable for high load and marked friction heat effect conditions.