The effect of oxygen on the dislocation structures in Vanadium

Abstract

A predominance of straight screw dislocations is observed in b.c.c. metals deformed at large effective stresses, i.e. low temperatures. This observation has been used as evidence that the double kink mechanism is the rate controlling mechanism of dislocation motion. If interstitial atoms were the short range barriers to dislocation motion, then a significant density of edge dislocation should be observed in samples deformed at large effective stresses. An investigation of vanadium containing various levels of oxygen (15–1000 wt.-p.p.m.) was undertaken. The samples were deformed at small and large effective stresses in both tension and compression. One of the most significant observations was the predominance of screw dislocations in samples deformed at large effective stresses, independent of oxygen concentration. Therefore, the interstitial oxygen atoms cannot act directly as short range barriers to dislocation motion.