Effects of cryogenic temperatures on mechanical behavior of a Zr60Ni25Al15 bulk metallic glass

The effects of cryogenic temperatures on mechanical behavior of a Zr60Ni25Al15 bulk metallic glass (BMG) with high glass-forming ability were investigated. With lowering the temperature from 293 K to 77 K, the compressive yield stress of the BMG increases from 1791 MPa to 2217 MPa, and the compressive plastic strain enhances from 3.5% to 16.7%. Similarly, the BMG exhibits an enhanced tensile fracture stress of 2036 MPa and a distinct tensile plastic strain of 0.14% at 77 K, compared to those of 1743 MPa and 0 at 293 K, respectively. In addition, the elastic moduli and Debye temperature of the BMG increase monotonously with decreasing temperature. The mechanisms of enhanced strength and plasticity of BMGs at cryogenic temperatures are discussed in terms of the inter-atomic bonding and the mobility and coalescence of free volumes.