FAILURE CRACK ORIENTATION AT DUCTILE SHEAR FRACTURE OF FE80-XNIXB20 METALLIC-GLASS RIBBONS

Orientation of failure cracks of oblique mode at ductile shear fracture are measured for Fe80-xNixB20 (x=10, 20, 30, 40, 50, 60) metallic glass ribbons (MGR) uniaxially extended with strain rate {Mathematical expression} from 3.3×10-6 to 1.25×10-3 s-1 at temperatures 300, 77 and 4.2 K. An angle between the failure crack and tension axis is found to depend non-monotonously on nickel concentration x and strain rate {Mathematical expression}. These dependences are probably due to the presence of dilatancy in shear bands and its variation as a function of concentration, strain rate and temperature. Mean values of quenching stresses in ribbons are estimated by comparing experimentally measured values and those predicted by T. Thomas in 1953. © 1990 Chapman and Hall Ltd.