Improving the mechanical performance of Cu[sbnd]Cr alloy by dissolving Cu in the Cr second phase

The strengthening effects of Cr on Cu[sbnd]Cr alloys are severely limited due to the relatively low solid solubility of Cr in Cu phase. Apart from the dissolved Cr, it should be noted that a high proportion of Cr in Cu matrix work as the second phase dispersion strengthening. To effectively improve the strengthening effect of Cr in Cu[sbnd]Cr alloys, it is important to enhance the dispersion strengthening effect of the second phase Cr. In this work, the Cr phase could be strengthened by dissolving Cu atoms through the levitation melting method (LM), without additional alloying element was introduced. The results show that a maximum of Cu (0.46-0.54 wt%) is dissolved into Cr phase in Cu₂Cr₉₈ and Cu₅Cr₉₅ alloys. The corresponding hardness is 38% and 56% higher for Cu₂Cr₉₈ and Cu₅Cr₉₅ alloys compared with pure Cr, respectively. This novel strengthening mechanism of the enhanced Cr second phase is further applied in CuCr₂₅ alloys. It is confirmed that the hardness is 57% higher for CuCr₂₅ with enhanced Cr phase than that prepared using conventional methods. Furthermore, the significant strengthening effect is confirmed in the tribological properties. This strategy can be utilized to effectively enhance the mechanical performance of Cu[sbnd]Cr alloys with high Cr content.