Microstructural characterization of (Ni, Cu) Al intermetallic compounds rapidly solidified

In order to investigate the effect of Cu-macroalloying and rapid solidification processing on NiAl intermetallic compounds, six alloys were studied. Four alloy compositions were inside the β-NiAl field, one alloy composition was in the upper limit of the β-NiAl field and one was far from this β-NiAl field going to the (β-NiAl–Cu3Al) field. Lattice constant showed a continuous increase as the copper content increased. TEM observations carried out in as-rapidly solidified ribbons showed the presence of elongated β-NiAl grains in alloys with Cu contents <20 at.%. In alloys with Cu content >20 at.%, the presence of second phase particles of Cu3Al was detected. Microhardness Vickers values in the rapidly solidified ribbons were always lower as compared with the as-cast ingots. Room temperature ductility of a (Ni, Cu) Al alloy showed values of 190.1 MPa of 0.2% yield strength, 293.3 MPa of ultimate tensile strength and 2.37% of elongation.