Effect of Al/Sc atomic ratio on the electrical conductivity,mechanical properties, and thermal stability of pure copper

This study examined the impact of the Al/Sc atomic ratio on the electrical conductivity, mechanical properties, and thermal stability of pure copper. By regulating the Al/Sc atomic ratio within the range of 1-3, the microstructure of the alloy was characterized via OM, EBSD, and TEM, among other methods. The results demonstrated that when the Al/Sc atomic ratio was approximately 3, the overall performance of the alloy was the most favorable. After a series of processing treatments, the conductivity, hardness and tensile strength in the coldrolled state are 87.2 % IACS, 145 HV and 396 MPa respectively, and the softening temperature is approximately 510 degrees C. After being treated at 850 degrees C for 30 min, the conductivity increases to 95.6 % IACS, the hardness decreases to 57.4 HV, and the average grain size is 72.92 mu m. When the atomic ratio of Al/Sc is approximately 3:1, under high-temperature conditions, Sc atoms almost entirely take part in the formation of oxide precipitation phases (such as Al2O3 and AlScO3), preventing the formation of excessive Sc solid solution or coarse phases (such as AlSc2). Furthermore, a large quantity of spherical Al2O3 precipitated phases with a size of approximately 6.9 nm, which are dispersed within the grain boundaries, have been formed. These small-sized particles offer a high density of pinning points. Simultaneously, ellipsoidal AlScO3 precipitated phases with a size of approximately 18 nm have been formed on the grain boundaries,The larger particles can effectively stabilize the grain boundaries and inhibit their migration rate under high temperatures, thereby significantly improving the strength and thermal stability of the alloy.