EFFECT OF Cr AND Ni ELEMENTS ON THE MICROSTRUCTURE AND PROPERTIES OF Cu-Fe-BASED IMMISCIBLE ALLOYS

The immiscible Cu-Fe system is often used as a base for advanced heterogeneous alloys. With a suitable selection of alloying elements, it is possible to alloy individual phases and therefore tailor microstructure and final properties of a material as needed. To prepare the mentioned multicomponent alloys, it is necessary to understand the effect of individual alloying elements on the microstructure and properties of the Cu-Fe system. Although mostly used method in production of such materials is casting, mechanical alloying appears to be a suitable alternative, enabling a very fine microstructure to be created. The following study is focused on the characterization of Cu50Fe25Cr25 and Cu50Fe25Ni25 alloys and the effect of the alloying elements on their microstructure. Cr and Ni were selected as a BCC and FCC phase enhancing elements, respectively. The alloys were prepared by mechanical alloying using high-energy ball mill, with subsequent densification using spark plasma sintering. The microstructure of milled powders, as well as bulk samples, was examined, and the evolution of the microstructure during sintering evaluated with respect to the alloying elements. In addition, the hardness of bulk samples was measured. During the mechanical alloying a complete mixing was not achieved, as the milled powders were not single phase. However, a metastable FCC supersaturated solid solution was formed at least partially in both alloys, further decomposing into a multiphase microstructure after sintering