Modification of tribology and high-temperature behavior of Ti–48Al–2Cr–2Nb intermetallic alloy by laser cladding

In order to improve the tribology and high-temperature oxidation properties of the Ti–48Al–2Cr–2Nb intermetallic alloy simultaneously, mixed NiCr–Cr3C2 precursor powders had been investigated for laser cladding treatment to modify wear and high-temperature oxidation resistance of the material. The alloy samples were pre-placed with NiCr–80, 50 and 20%Cr3C2 (wt.%), respectively, and laser treated at the same parameters, i.e., laser output power 2.8 kW, beam scanning speed 2.0 mm/s, beam dimension 1 mm 18 mm. The treated samples underwent tests of microhardness, wear and high-temperature oxidation. The results showed that laser cladding with different constitution of mixed precursor NiCr–Cr3C2 powders improved surface hardness in all cases. Laser cladding with NiCr–50%Cr3C2 resulted in the best modification of tribology and high-temperature oxidation behavior. X-ray diffraction (XRD), optical microscope (OM), scanning electron microscopy (SEM) and energydispersive spectrometer (EDS) analyses indicated that the formation of reinforced Cr7C3, TiC and both continuous and dense Al2O3, Cr2O3 oxide scales were supposed to be responsible for the modification of the relevant properties. As a result, the present work had laid beneficial surface engineering foundation for TiAl alloy applied as future light weight and high-temperature structural candidate materials.