ABSTRACT

The thick titanium nitrides coating was fabricated on LZ91 alloy by surface mechanical nano-alloying (SMNAT) combined with gas nitriding. Experimental results showed that a nanostructured titanium coating with thickness of 50–80 μm was formed on surface of LZ91 alloy by SMNAT with pure titanium powders for 30 min. By adding of the aluminium powders into titanium powders during the SMNAT, a thicker Ti-Al composite coating with improved continuity and uniformity was obtained. After nitriding at 450°C, the whole Ti and Ti-Al coating were successfully nitrided. The surface layer of nitrided Ti coated sample is mainly composed of TiN, Ti₂N, TiN_0.3, TiN_0.61 and Ti₄N_2.33 phases and the surface layer of nitrided Ti-Al coated sample is composed of Ti₂N, TiN_0.9, TiN_0.3, Ti₄N_2.33, AlN, Ti₃Al₂N₂ and AlTi₂N phases. The hardness measurements demonstrated that the surface hardness of nitrided Ti coated and nitrided Ti-Al coated samples reached to 634 and 734 HV, respectively.

摘要

通过表面机械纳米合金化 (SMNAT) 结合气体氮化在 LZ91 合金上制备厚氮化钛涂层。实验结果表明，用纯钛粉末经 SMNAT 处理 30 分钟，在 LZ91 合金表面形成了厚度为 50-80 μm 的纳米结构钛涂层。通过在 SMNAT 过程中将铝粉添加到钛粉中，获得了更厚的 Ti-Al 复合涂层，具有更好的连续性和均匀性。在 450°C 渗氮后，整个 Ti 和 Ti-Al 涂层均成功渗氮。氮化钛涂层样品的表层主要由TiN、Ti ₂ N、TiN _0.3、TiN _0.61和Ti ₄ N _{2.33 组成}相和氮化Ti-Al涂层样品的表面层由Ti ₂ N、TiN _0.9、TiN _0.3、Ti ₄ N _2.33、AlN、Ti ₃ Al ₂ N ₂和AlTi ₂ N相组成。硬度测量表明，氮化钛涂层和氮化钛铝涂层样品的表面硬度分别达到 634 和 734 HV。