Thermo-mechanical fatigue of a SiC_W/6061Al composite

In-phase (IP) and out-of-phase (OP) thermo-mechanical fatigue (TMF) experiments were undertaken on 6061 aluminum alloy reinforced with 15% volume fraction whiskers. Both TMF tests were conducted under mechanical strain range control with temperature cycling between 150 - 300°C. The mechanical behavior and fatigue resistance of both TMF fatigue was investigated and discussed. The result shows that the two kinds of TMF cycling exhibited continuous cyclic softening, out-of-phase TMF loading gave rise to tensile mean stress, whereas in-phase TMF cycling led to compressive mean stress. It is also illustrated that at small strain range, the in-phase TMF life was longer than that of the out-of-phase TMF; on the contrary, out-of-phase TMF showed longer life at large strain range. This is tentatively explained by the various damage mechanisms with the help of SEM, which were predominantly operative under different strain ranges and different phasing conditions.