Accelerated property evaluation of Ni-Co materials libraries produced by multiple processing techniques

Ternary iron-cobalt-nickel (Fe-Co-Ni) alloys have many structural and magnetic industrial applications. The counterpart binary Ni-Co alloys, which are used in energy systems, have been much less studied than Fe-Co and Fe-Ni alloys. The properties of Ni-Co alloys depend sensitively on the processing methodology. However, a systematic evaluation of the effect of processing on the properties has not been carried out. Hence in this work, we studied multiple properties of NixCo1-x material libraries processed by three different techniques. Ni-Co powders were produced by low temperature chemical reduction, compositionally graded alloys were produced by spark plasma sintering (SPS) of powders, and bulk alloys were processed by arc melting. The structural, magnetic, mechanical, and electrical properties of the Ni-Co alloys produced by these techniques were determined via an accelerated methodology. The crystal structure, coercivity, resistivity and hardness of the alloys varied significantly with the processing technique. The powder samples exhibited highest Hc values, while the lowest Hc, highest microhardness and electrical resistivities were obtained in SPS samples. The broad change in properties with composition and processing techniques provides a rich opportunity to select both the composition and the processing techniques needed for specific applications.