TA2钛合金表面激光熔覆Ni基Tribaloy700涂层

Laser Cladding Ni-Based Tribaloy 700 Coatings on TA2 Titanium Alloy

为提高钛合金表面强度，采用预置Trihaloy700（T7（）0）合金粉末的方法在TA2钛合金表面进行了激光熔覆制备Ni基T700涂层的研究。研究结果表明，通过激光熔覆能够获得良好的T700合金涂层；涂层中Ti的适量存在能够促进laves相的析出与长大，Ti稀释较小时涂层组织主要为胞状和胞一枝蔓状的奥氏体7Ni相，而Ti稀释较大时涂层组织为基体（TiNi＋7Ni相）＋Laves相；涂层与基材之间有一厚约80～100μm的过渡区。显微硬度测试结果表明，在固溶强化及细晶强化等作用下T700熔覆涂层的显微硬度较常规方法有明显提高，适量的Ti稀释能够进一步提高涂层的硬度。根据Ti稀释程度的不同，涂层的平均硬度值在7001000HV之间，约比TA2钛合会基材高4～5倍。

Laser cladding coatings of TA2 titanium alloy with preplaced Tribaloy700（T700） powder to fabricate Nibased tribaloy 700 coatings are experimentally studied for developing a hardfacing process of titanium alloy. Ni-based alloy coatings without cracks and pores on the boundary are obtained, The dilution of Ti will expedite the separation and growth of laves phases. Microstructure of the coating consists of mainly γ-Ni phase in cell and dendrite structure with less dilution of Ti and matrix （TiNi ＋ γ-Ni） ＋laves phases in large dimension with more dilution of Ti. The transition region between the coating and substrate is about 80 - 100 μm thick. Microhardness test results show that, with solution strengthening and grain refinement, the microhardness of T700 coatings is higher than that of routine methods. The dilution of Ti will increase the microhardness dramatically. The microhardness of the coatings ranges from 700HV to 1000HV according to dilution ratio of Ti, and the microhardness are four to five times higher than that of TA2 alloy.