Metallic Glass Coating for Enhancing Fatigue Property

Compared to conventional crystalline films and ceramic hard coatings, thin film metallic glasses (TFMGs) have unique properties such as high strength, high toughness, large elastic limit as well as excellent wear and corrosion resistances. Therefore, coatings of TFMGs with these advantages are beneficial to enhance the substrate fatigue property such as high hardness to prevent the surface roughening; good ductility and toughness to prevent crack initiation from the place where persistent slip bands intersect the film; high compressive residual stresses to retard the crack propagation into the substrate; and good adhesion to prevent coating delamination.

In this presentation, we will discuss the fatigue behavior of various crystalline alloys and bulk metallic glass (BMG) substrates coated with TFMGs. Four-point-bending fatigue tests are conducted on 316L stainless steel, Ti6Al4V, Mg-based alloy, and Zr-based BMG, which are loaded at various stress levels at R ratio of 0.1 within a 10 Hz sinusoidal waveform. The results show that the fatigue properties of the substrates are greatly improved after coating. Moreover, the annealed TFMGs can improve the fatigue property further than the as-deposited TFMGs, which is attributed to more homogenous structure of TFMGs obtained after annealing.