MECHANISM OF BORON-INDUCED DUCTILITY IN POLYCRYSTALLINE NI3AL

A mechanism is proposed to explain the change in the ductility of Ni-rich Ni3Al on addition of small amounts of boron. It is argued that grain boundary segregationof B is not the cause of the increase in ductility. Instead, Ni-B bonds and antisite Nidefects reduce the directionality of the bonding in ordered Ni3Al and enhance theductility in the interior of grains so that deformation can be easily transmitted fromone grain to another. Experimental evidence for this model is presented. An estimateof the concentration of B to achieve maximum ductility is made and the estimateagrees well with the experimental value. © 1990 Taylor & Francis Group, LLC.