Effects of Fe content on properties and microstructure of Cu–Ti alloys during aging

Abstract

In this study, Cu-2.7Ti-0.2Fe (CT-0.2Fe) and Cu-2.7Ti–1Fe (CT-1Fe) alloys were fabricated and underwent multi-stage thermomechanical treatment, and the microstructure and properties evolution of the alloys during aging were investigated. After aging for 60 h at 350 °C, the CT-0.2Fe and CT-1Fe alloys exhibited the yield strength of 1068/935 MPa, tensile strength of 1127/1057 MPa, elongation of 2.54%/2.21%, and electrical conductivity of 20.3/26.4 %IACS, respectively. The relatively higher electrical conductivity of CT-1Fe was primarily attributed to the formation of numerous TiFe particles. Typical modulated structure and β′-Cu4Ti precipitates formed during direct aging in both alloys. However, in the CT-1Fe alloy, the growth of β′-Cu4Ti precipitates was suppressed. During multi-stage thermomechanical treatment, the interaction of the dislocations and precipitates was enhanced, retarding the softening effects of the alloy at the elevated temperatures. The calculation results showed that work hardening and precipitation strengthening significantly contributed to enhancing the mechanical properties of the alloys.

Keywords

• Cu-Ti-Fe alloys
• Multi-stage thermomechanical treatment
• β′-Cu4Ti precipitates
• Mechanical properties