Deformation behavior of partially crystallized Zr57Ti5Al10Cu20Ni8 bulk amorphous alloy

Annealing of the Zr57Cu20Al10Ni8Ti5 amorphous alloy near the glass transition temperature produces microstructures of nanocrystals embedded in an amorphous matrix. The crystallization becomes retarded when the crystal amount reaches about 40 vol%. The deformation behavior of the partially crystallized alloys were measured by compression test at room temperature and at elevated temperature. The partially crystallized alloy shows higher yield stress and fracture stress(with the highest value of about 1800 and 1950 MPa, respectively) than the as-cast amorphous alloy (1560 and 1650 MPa, respectively). The fracture stress and the elastic deformation begin to decrease when the crystalline fraction is above 45 vol%. Compressive tests at elevated temperature shows that the stress for viscous deformation of the partially crystallized alloy (with about 40% crystals) does not change significantly in comparison with the amorphous alloy. These results indicate that such bulk amorphous alloy can be hot-worked (shaped) at elevated temperature. (C) 1998 Elsevier Science B.V.