Microstructure and Properties of Laser Cladding Ni/Al-Cu Coating on TC21 Titanium Alloy

Laser cladding technology was used to prepare Ni/Al cladding layer with Cu content of 0, 4, 8at% on the surface of TC21 titanium alloy.Using scanning electron microscope (SEM), X-ray diffractometer (XRD), microhardness tester and material surface performance comprehensive tester, the influence of Cu element on the microstructure and performance of Ni/Al cladding layer were studied.The results show that when Cu element content is 0at%, the cladding layer phase is mainly composed of TiNi, Ti₂Ni, TiAl, AlNi₂Ti, and there are holes in the microstructure of the cladding layer. With the addition of Cu, Cu atoms replace Ni atoms in the TiNi crystal structure, forming a new ternary phase TiNi_0.8Cu_0.2, and the cladding layer has a dense structure. When the Cu element content is 4at%, the cladding layer has the highest microhardness and wear resistance, the hardness is about 2.3 times of the substrate, and the wear resistance is 4.1 times of the substrate. The wear mechanism is mainly adhesive wear and abrasive wear.