Effect on mechanical properties of Zr55Cu30Al 10Ni5 bulk metallic glass by thermoplastic deformation

The bulk metallic glass (BMG) is highly expected for the new structural material by its various excellent properties such as the high strength, the corrosion resistance and so on. Moreover, it can show the superplastic deformation in a high temperature condition, although it has very little plastic deformation in the room temperature. The excellent properties of BMG are caused by its amorphous structure, but its atomic structure tends to change into crystalline structure across TTT curve through a thermal process in a high temperature. Therefore it is important for an application of BMG to study not only its workability with plastic deformation at high temperature but also its mechanical properties at room temperature after thermoplastic deformation. In this paper, the effect on the strength of Zr55Cu30Al 10Ni5 bulk metallic glass at room temperature by heating process or thermoplastic deformation in high temperature is mentioned. This material had the tendency to exceed easily its TTT curve and crystallize by heating beyond 685K in a furnace. And the strength of crystallized material at room temperature drastically decreased, while this material as cast with amorphous structure had the high strength. On the other hand, it was made sure that this material could be sufficiently deformed plastically at 667K (18K lower than 685K), and furthermore, it maintained the high strength similar to Zr 55Cu30Al10Ni5 BMG as cast. © 2007 The Society of Materials Science.