Enhanced Tensile Strength and Plasticity of Zr-Cu-Al Bulk Glassy Alloys at Cryogenic Temperatures

Abstract

No data are available about mechanical behavior of bulk glassy alloys (BGAs) in tension at cryogenic temperatures. In this study, we investigated the effect of temperature on the mechanical behavior of ternary eutectic and hypoeutectic Zr-Cu-Al BGAs fabricated by an arc tilt casting method. Tensile tests were performed for the BGA plates with gauge dimensions of 5 mm in length, 1.2 mm in width and 0.5 mm in thickness at temperatures of 295, 223, 173 and 77 K, at an initial strain rate of 5 10 4 s 1 . Measurements of elastic parameters were also made at temperatures from 97 to 342 K by an ultrasonic pulse method. It is found that the tensile strength and elongation for both BGAs increase with decreasing testing temperature, which is reported for the first time under a tensile condition. At cryogenic temperatures, the tensile elongation of the hypoeutectic Zr59Cu31Al10 BGA tends to be higher than that of the eutectic Zr50Cu40Al10 BGA, although the difference is small. Multiple shear bands are observed on the side surface deformed at lower temperatures. The Young’s and shear moduli, and Debye temperature monotonically increase with decreasing temperature. This indicates that the BGA becomes rigid and the effective atomic distance decreases at cryogenic temperatures, leading to the increase of the tensile strength at cryogenic temperatures. [doi:10.2320/matertrans.M2009186]