An investigation of microstructure and mechanical properties in Cu–Ti–Sn alloys rich in copper

The microstructure and hardness evolution of three alloys based on the system Cu–Ti–Sn, rich in copper, have been investigated (CuTi2 wt.%Sn2.75 wt.%, CuTi3 wt.%Sn2.75 wt.% and CuTi4 wt.%Sn2.75 wt.%). They are characterised by the presence of the ternary eutectic intermetallic CuTi3Sn5 in the as cast state. Suitable thermomechanical treatments cannot dissolve this phase. The effect of a variation in Ti content during ageing was studied by microstructure observations (S.E.M.), chemical analysis (W.D.S.), D.T.A, X.R.D. and hardness testing (Vickers). The low hardness obtained led to consider a chromium addition in CuTi4 wt.%Sn2.7 5wt.%. As for last materials, the microstructure of this alloy is related to its Vickers hardness.