Deformation mechanism of amorphous and partially crystallized alloys

The deformation behaviour of Zr-5-Ti5Cu20Ni8Al10 amorphous and partially crystallized alloys was studied by compressive test. Precipitates of micrometer size (mu m) have serious effect on initiating cracks leading to early fracture. Precipitates of 2-10 nm exhibit effect of increasing yield stress and fracture stress but do not exhibit significant effect to initiate cracks when the crystalline volume fraction is below about 40%. Vein pattern is the characteristic fracture morphology of alloys with amorphous matrix. It is formed during the quick final fracture from a viscous layer along the fracture plane which is formed due to local adiabatic heating by the work of plastic shear. The plastic deformation of amorphous alloys is in fact composed of sections of elastic deformation. Each section of the elastic deformation is followed by local quick plastic shear deformation in the specimen to release stress. (C) 1999 Acta Metallurgica Inc.