The influence of heat treatment on the structural phase state and durometric properties of small-sized castings from a copper alloy Cu-Cr-Al

The effect of heat treatment on the structural-phase state and hardness of small-sized castings made from the Cu-Cr-Al copper alloy obtained by casting in a water-cooled metal mold is studied. Using X-ray diffraction analysis, it was found that the castings consist of a matrix solid solution based on copper. The increased value of the crystal lattice parameter of the copper phase is associated with aluminum atoms dissolved in it. After a low-temperature (450 °C) tempering for 10 hours, the crystal lattice parameter of the matrix solid solution decreases, which is associated with the formation of the Al8Cr5 intermetallic compound on the surface of the casting. It is established that after heat treatment (hardening and tempering), the hardness of castings from the Cu-Cr-Al alloy increases by 1.5 times.