Effect of copper alloying on the deformation behavior of B2 NiAl intermetallic compounds

Abstract

The effects of copper addition on the compressive deformation behavior of B2 NiAl intermetallic alloys were investigated. Experimental NiAlCu alloys were vacuum melted and hot extruded at 1273 K at a 18:1 reduction ratio. Compressive flow behavior was analyzed over a temperature range from 298 to 1073 K. An increase in room temperature hardness by addition at 10 at% Cu was observed in near stoichiometric NiAl-z.sbnd;Cu alloys but hardnesses were lower in nickel-rich NiAlCu alloys than in binary NiAl. No considerable improvement in room temperature ductility was observed in NiAl containing 10 at% Cu. Significant improvement in compressive ductility was observed in copper-micro-alloyed (less than 1%) near stoichiometric NiAl. Fracture strains were in the range 1.25–0.35 at room temperature and reached 0.8 at 473 K. At over 673 K, copper-microalloyed NiAl deformed in an almost perfectly plastic manner. The sources of improved ductility are discussed.