Thermo-mechanical fatigue of SiC whisker reinforced 6061Al composites - II. Fatigue life and damage mechanism

The In-phase (IP) and out-of-phase (OP) thermo-mechanical fatigue (TMF) life and damage mechanism were studied on 15%SiCW (volume fraction) and 28%SiCW/6061Al. The result indicates that in small strain range, the IP TMF life is longer than that of the OP-TMF; in large strain range it is close to (for 28%SiCW) or even shorter than the OP-TMF life (for 15%SiCW). A comparison of the fatigue lives between the two composites illustrates that in the case of the OP-TMF, 15%SiCW/6061Al shows longer life than 28% SiCW/6061Al, however, in the case of IP-TMF, there is a crossover between the fatigue life curves of the two composites, meaning that the life being longer or shorter depends on strain level. Their damage processes are all related to initiation, growth and coalescence of voids in the matrix around whiskers.