Adhesion Behaviour, Nanohardness and Surface Roughness of Ti–6Al–4V–6B₄C Thin Films Grown on AISI 1040 Steel

Abstract

The nanohardness of Ti–6Al–4V–6B₄C thin film coated AISI 1040 steel were investigated using nanoindentation based on an AFM measurement technique. Thin films of Ti–6Al–4V–6B₄C were grown by the magnetron sputtering deposition method. X-ray diffraction analysis revealed that the deposited thin films were highly purified. The nanohardness of 18, 14 and 11.3 GPa were obtained for the coating of Ti–6Al–4V–6B₄C, Ti–6Al–4V, and bare substrate respectively. The surface roughness (R_a) of 0.5 and 1 h coating were 3.39 and 15.74 nm respectively. The results showed that the B₄C particles had a significant effect on the microstructural and mechanical properties of the coatings. The Ti–6Al–4V–6B₄C coating was obtained for a coating thickness of 40 and 100 nm for 0.5 and 1 h coating time respectively. In the meantime, the respective coating thickness of Ti–6Al–4V was obtained as 30 and 80 nm for 0.5 and 1 h coating time respectively. Strong adhesion was observed between the Ti–6Al–4V–6B₄C coating and AISI 1040 steel substrate than Ti–6Al–4V samples. The adhesion mechanism between the Ti–6Al–4V–6B₄C coating, AISI 1040 steel substrate, and the interfacial structure were studied by using scanning electron microscope (SEM). The use of Ti–6Al–4V–6B₄C coating could be a novel technique for developing high-performance applications due to excellent adhesion and nanohardness.