NER: Nanoscale Clusters in the Design of Ductile Cr Base Alloys

Northwestern University, Evanston IL

Investigators

Abstract

Nanoscale Clusters in the Design of Ductile Cr Base Alloys Morris E. Fine, Arthur J. Freeman, David N. Seidman and Johannes Weertman Nanocrystalline embedded particles in materials are currently subjects of great interest in basic solid state physics and also because of possible useful applications. Chromium's use is highly restricted because it lacks ductility at room and lower temperatures. If the room temperature ductility could be increased substantially chromium alloys would find extensive use to save weight because of its very high modulus to density ratio and at high temperatures because its melting temperature is substantially higher than that of nickel. Coherent nanoscale clusters are proposed to increase the ductility of chromium at ambient temperatures by lowering the Peierls stress for screw dislocations. Clustering of solute atoms in chromium will be investigated from first principles by ab-initio computation and experimentally with the three-dimensional atom probe. Their effect on ductility will be fundamentally investigated by determining the flow stress versus temperature and strain rate. The interaction of embedded particles with dislocations will be advanced theoretically