The invention relates to a method for improving strength and
conductivity of a smelted and cast Cu-Cr-Nb
alloy, and belongs to the field of
copper alloy materials. The
alloy is mainly prepared from Cu, Cr, Nb and M, the proportion of Cr is 0.5-2.5 wt.%, the proportion of Nb is 0.1-1.0 wt.%, the proportion of M is 0.1-0.50 wt.%, and the balance is
copper. The M is composed of at least four elements of RE, Ag, B, P, Si, Ca, Li, Mg, Ti, Fe, Zr and Mn, and the RE is selected from at least one of Ce, La, Y, Pr, Nd, Sm, Sc, Gd and Dy. According to the method, the microalloying element M is added into the alloy, and the large-size high-strength high-
conductivity Cu-Cr-Nb-M alloy which is fine in structure and uniform in component is prepared through
smelting,
casting and thermomechanical treatment. A
metal mold is used as an inner mold and surrounds a
cooling pipe, a sand mold is used as a special combined mold of an outer mold, and the melt solidification rate is increased through cooling water. By means of the combined action of M microalloying, rapid solidification and thermomechanical treatment, the structure of the alloy is regulated and controlled, the performance of the alloy is improved, a multi-scale multi-phase, fine-grain, sub-grain and
dislocation entangled
microstructure is obtained, direct
casting forming of the large-size Cu-Cr-Nb alloy is achieved, and synchronous improvement and good matching of the strength and the electric
conductivity are achieved. The process is simple, the production cost is low and the application prospect is good.