Accumulative HPT of Zr-based bulk metallic glasses

Abstract

Studies show that with the HPT of bulk metallic glass, the actual achievable strain is significantly lower than the one predicted by the equation γ=2πnR/h. Such a discrepancy can be explained by the effect of “slippage” during the HPT. The authors proposed a new method − “accumulative HPT” − to achieve a high strain in hard materials, including BMGs. In the accumulative HPT procedure, a sample undergoes several cycles: “HPT n = 1 revolution → cutting a sample into pieces → pressing of stacked parts on the anvils and subsequent HPT n = 1”. At the last stage, the stacked segments are subjected to HPT with many revolutions (n ≥ 3) whereby the sample is consolidated into a monolithic disk. As a result, the material receives a significant total strain by pressing and torsion. The article presents the first results of the “accumulative HPT” processing of a Zr-based BMG and a crystallized Zr-based intermetallic.