Fabrication of CuZr(Al) bulk metallic glasses by high pressure torsion

In this paper, pure Cu, Zr and Al metal sheets were alternatively stacked and, then, cold roll-bonded. The overall compositions of the stacks were Cu71Zr29, Cu62Zr38, Cu53Zr47 and Cu52Zr38Al10. The bonded materials were subsequently sliced into disks and, then, used for high pressure torsion (HPT) process. After HPT process up to maximum equivalent strain of about 1200 at ambient temperature, bulk materials with 10 mm in diameter and 0.30 mm in thickness were obtained. The phase constitution and microstructural evolutions of the HPTed samples with various rotations ranging from 0.5 to 20 were studied by XRD, FESEM and TEM. Thermal properties of the HPTed samples were analyzed by DSC. It was found that CuZr(Al) BMGs could be fabricated with a wide composition range by the HPT process. Tensile tests were used to measure the mechanical properties of the HPT processed samples. The mechanism of the solid-state amorphization during the HPT process was put forward and discussed.