Investigation on Nano-tribological Properties of Amorphous Alloys Based on High-throughput Co-sputtering Method
A Pd-W-Si amorphous alloy library with different compositions is prepared by a high-throughput method based on magnetron co-sputtering.The effects of indentation hardness(H)and elastic modulus(E)on the nano-tribological properties of the amorphous alloys are investigated by experiments of nanoindentation and nanoscratch.It is found that:(1)although the scratch depth(hs)follows a decreasing trend with increasing hardness and elastic modulus,the matching degree of data points with the trend line is stronger for elastic modulus as compared with hardness,which can be rationalized by the volume of shear transformation zone(STZ)that suggests the more difficult activation of the deformed unit in amorphous structure and thus the better scratching resistance:for the alloy with large H and E,the STZ volume is estimated to be small,resulting in a shallow scratch depth and high scratch resistance,while the fluctuation of STZ volume with E is weaker than H.(2)The correlation of elastic recovery(η)is weak with hardness but strong with H/E.In particular,the elastic recovery increases with H/E.This is because,for the alloy with high H/E,the energy absorbed in an elastically deformed regime is more and the material after elastic-plastic deformation is easier to recover;the phenomenon that the pile-up height of amorphous alloy decreases with H/E also promotes the free slipping of shear bands to a certain extent,thus leading to higher elastic recovery and better wear resistance.
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