Deformation mechanism of amorphous and partially crystallized alloys

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