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采用一种反应熔敷法,在钽合金表面制备一层较厚的碳化物强化层,进行钽合金的表面强化。以TaW12合金板材作为基板,将Ta粉和C粉混合,均匀涂覆在TaW12合金板材表面。以电弧为熔敷热源,在整个粉末涂覆面上进行逐行扫描,引发混合粉末与基板的反应熔融和固相扩散,获得表面硬化层。表面熔敷层完全致密,为熔融结晶状态。外表面呈周期性的波浪形,无裂纹,无气孔显现。熔敷层主要是Ta2C相与钽固溶体混合的共晶凝固组织,等轴状和条状的Ta2C相分布在Ta合金基体上,呈现一定的方向性,大多数近似垂直于板面。熔敷层与基体之间有一层由固态扩散产生的组织,大量针状Ta2C相在基体上交叉析出,形成网状结构。Ta2C相尺寸由外向内变小,逐步成为细小点状析出。熔敷层与过渡层间为固液界面,结合非常好,无裂纹和空洞存在。表面熔敷层平均维氏硬度为6690MPa,达到了基体材料硬度的3倍。过渡层中硬度急剧下降,为熔敷层的一半。
A reactive deposition method is used to prepare a thicker carbides reinforcement layer on the surface of the tantalum alloy for surface strengthening of the tantalum alloy. TaW12 alloy plate as a substrate, the Ta powder and C powder mixed uniformly coated on the surface of the TaW12 alloy sheet. The electric arc is used as a heat source for melting, and a line-by-line scan is performed on the entire powder coating surface to cause reactive melting and solid phase diffusion of the mixed powder and the substrate to obtain a surface hardened layer. Surface cladding layer is completely dense, melting crystalline state. The outer surface of the periodic wavy, no cracks, no stomata appear. The deposited layer is mainly composed of Ta2C phase and tantalum solid solution mixed eutectic solidification structure, equiaxed and strip Ta2C phase distribution in Ta alloy matrix, showing a certain direction, most of the approximately perpendicular to the plate surface. Between the cladding layer and the substrate, there is a layer of microstructure formed by the solid state diffusion. A large amount of acicular Ta2C phase is precipitated on the substrate to form a network structure. Ta2C phase size smaller from the outside to the inside, and gradually become a small dot-like precipitation. Fusion layer and transition layer between the solid-liquid interface, the combination is very good, no cracks and voids exist. The average Vickers hardness of the surface cladding layer is 6690 MPa, which reaches 3 times of the hardness of the base material. The hardness of the transitional layer dropped sharply, half of the cladding layer.