Mean stress effects on flow localization and failure in a bulk metallic glass

The effect of stress state on strain localization and subsequent failure of a bulk metallic glass alloy is examined. It is shown that failure is associated with a critical tensile mean stress of 0.95 GPa. This is in contrast with previous work utilizing superimposed compressive mean stresses, which found that failure resulted at a critical effective stress. Interestingly, the critical tensile mean stress measured in this study causes the same dilatation as a 274 K temperature increase, nearly to the glass transition temperature. The effect of mean stress on elastic variation of the average free volume is added to a strain localization model. This model describes the compressive mean stress behavior very well, and predicts a strong sensitivity to tensile mean stresses. (C) 2001 Published by Elsevier Science Ltd on behalf of Acta Materialia Inc.