Zr5018Nil1AlTi10Ti5 bulk metallic glass has been rolled at room temperature up to 95% in thickness reduction, and the dependence of microstructure on the strain was investigated. With increasing thickness reduction, the full width at half maximum （FWHM） and crystallization enthalpy decrease gradually till 80%, and then increase evidently at 95%. It is revealed that the reversible transition between the ordered and disordered atomic configurations was found in the metallic glass as the deformation proceeds, which is further verified by the high-resolution transmission electron microscopy images. The final microstructure in metallic glass during cold-rolling is the net result of two competing processes between shear-induced disordering and diffusion controlled reordering.
Honghong YanYong HuZhijie YanXiaohua ZhengYongtang Li
The microstructure evolution of Zr60Al15Ni25 bulk metallic glass during rolling at room temperature is investigated by differential scanning calorimetry(DSC),high-resolution transmission electron microscopy(HRTEM) and selected area electronic diffraction(SAED).The HRTEM images show that shear bands are produced in the rolled specimens,indicating the essence of inhomogeneous deformation due to rolling,and that there exist nanocrystals with size of about 5-10 nm in the transition regions between the shear bands and the undeformed matrix in the rolled specimens with deformation degrees of 80% and 95%.Based on the polyhedral structure model and the shear transformation zone(STZ) theory,the influence of viscous flow,free volume,viscosity and the stress situation on the crystallization behaviors in the metallic glass during rolling is discussed.
YAN ZhiJie,YAN Jun,HU Yong & DANG ShuE School of Materials Science and Engineering,Taiyuan University of Science and Technology,Taiyuan 030024,China
