The coarsening of the precipitates in melt-spun Al–Ti–Zr ribbons

Two kinds of Al–Ti–Zr alloys were prepared to investigate the coarsening of the spherical L12-structured Al3(Ti,Zr) precipitates aging at 425 °C for various periods of time. The results indicated that the increasing of Zr-content would result in increasing the coarsening rate of the precipitates. The coarsening coefficients of L12-structured Al3(Ti0.25Zr0.75) and Al3(Ti0.75Zr0.25) precipitates in these Al–5 vol.% Al3(Ti,Zr) alloys are 3.94×10−28 and 1.61×10−28 m3 h−1, respectively. In addition, the higher Zr-content Al3(Ti0.25Zr0.75) precipitates became unstable and formed a kind of complex precipitates after aging for a long period of time. The hardness data shows that the peakaging of both two alloys were aging at 425 °C for 100 h, and the peakaging hardness of Al–0.65Ti–3.22Zr and Al–1.74Ti–1.14Zr alloys were HV 75 and HV 78, respectively. The hardness of Al–0.65Ti–3.22Zr alloy was slightly lower than that of Al–1.74Ti–1.14Zr alloy due to the faster coarsening rate of the Al3(Ti0.27Zr0.75) precipitates.