Size effect and anisotropy in cold rolled Zr-base bulk metallic glasses during nanoindentation

A series of instrumented nanoindentation tests have been performed in control loading rate mode on Zr52.5Cu18Ni14.5Al10Ti5 (VIT105) and Zr58.5Cu15.6Ni12.8Al10.3Nb2.8 (VIT106A) as-cast and various cold rolled samples to investigate the indentation size effect (ISE) in three perpendicular planes i.e., rolling-width (RW), normal-rolling (NR) and normal-width (NW) planes at peak loads in the range of 50 mN -500 mN. The hardness, reduced modulus and dynamic hardness have reduced with the increase of indentation depth in NR, RW and NW planes. The as-cast and cold rolled BMGs exhibit normal ISE for NR, RW and NW planes. The size effect has been analyzed using power law, Nix-Gao model, and proportional specimen resistance model suggesting that dynamic mechanical softening and the friction between the indenter and specimen are the underlying reasons behind the observed ISE.

Automated summary

A series of instrumented nanoindentation tests were conducted on Zr52.5Cu18Ni14.5Al10Ti5 and Zr58.5Cu15.6Ni12.8Al10.3Nb2.8 as-cast and cold rolled samples to investigate the indentation size effect in three perpendicular planes. The results showed that the hardness, reduced modulus, and dynamic hardness decreased with increasing indentation depth in the rolling-width, normal-rolling, and normal-width planes. The size effect was analyzed using various models, indicating that dynamic mechanical softening and friction between the indenter and specimen were the underlying reasons for the observed indentation size effect.