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 Â 10 À4 s À1 . 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 Zr 59 Cu 31 Al 10 BGA tends to be higher than that of the eutectic Zr 50 Cu 40 Al 10 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.

Cryogenic-temperature-induced transition from shear to dilatational failure in metallic glasses

“…Fig. 1a shows the tensile failure strength r f of Vitreloy 1 as a function of the environmental temperature T. The failure strength increases gradually with decreasing temperature from 300 to 77 K, which is consistent with the observations in other Zr-based metallic glasses [32][33][34][35]. However, with further decreasing temperature to 20 K, the failure strength is found not to increase any more, but starts to decrease instead.…”

Tensile Plastic Deformation Behavior of Zr₇₀Ni₁₆Cu₆Al₈ Bulk Metallic Glass at Cryogenic Temperature

“…In contrast, some recent results have indicated that the tensile plastic deformation of BMGs occurs at cryogenic temperature on the basis of experiments performed using Zr CuAl BMG, 7) ZrCu based BMG 8) and ZrNiCuAl BMG. 9) These results suggest that the tensile plastic deformation behavior of BMGs depends on the strain rate and temperature.…”

Ambient temperature embrittlement of a Zr-based bulk metallic glass

“…On the other hand, the strengthened materials at low temperature usually behave more brittle. However, very interestingly, it is reported that BMGs at cryogenic temperature show enhanced plasticity in compression [1][2][3][4][5][6][7][8], even in tension [9,10]. Such plasticity improvement was attributed to multiple-nucleation of shear bands at low temperature [1,5,7].…”

“…Similar to crystalline alloys, BMGs usually exhibit higher strength with the decrease of the ambient temperature [1][2][3][4][5][6][7][8][9][10]. Its underlying mechanism has been discussed in terms of shear transformation zones (STZs) [1,3,5,[10][11][12].…”