ENHANCED MECHANICAL AND SERVICE PROPERTIES OF ULTRAFINEGRAINED COPPER-BASED ALLOYS WITH Cr, Zr, AND Hf ADDITIVES
Structure and properties of low-alloyed copper-based alloys with Cr, Zr and Hf after severe plastic deformation (SPD) using techniques of high pressure torsion (HPT) and equal channel angular pressing (ECAP) have been studied. SPD significantly increases strength of the alloys by formation of ultrafine-grained structure. Cu5Zr and Cu5Hf particles suppress the grain growth in ultrafine-grained (UFG) structure more effectively than the Cr particles and provide additional hardening during aging. Moreover, it was found that the application of additional aging after SPD significantly improves service properties of the alloys (fatigue limit, wear resistance and electrical conductivity). This combination of properties results in a high durability of electrodes for resistance spot welding produced from UFG Cubased alloys.