Numerical approach for estimating the elastic modulus in MMCs as a function of sintering temperature

The main problem of metal matrix composite (MMC) when submitted to high temperature is the degradation of the reinforcement. Normally, this effect is studied through degradation at the interface of the reinforcement. In this case, the high temperatures produce the formation of intermetallic compounds. Generally, particle or whisker type reinforcements produce an improvement in the mechanical properties. In either case, to do a prediction of this influence through a mathematical model is very difficult and the single utilisation of the rule-of-mixtures is unsuitable for evaluating the effect that a discontinuous reinforcement would produce in these materials, because the different properties involved are very sensitive to the changes that occur in the microstructure during the production of the composite. This paper presents a numerical model to evaluate the Young’s modulus of the MMCs as a function of the sintering temperature. This model is similar to that presented in the rule of mixtures. However, it considers the porosity of the sintered material itself and the diffusion phenomena produced during the sintering of these materials. The suggested model utilises experimental data of the sample sintered in a vacuum at 1120, 1160, 1200, 1230 and 1250 °C for periods of 30 min. The Young’s modulus was obtained from the tensile curves of stress–strain. The utilised material is constituted of powder particles with size 99.8%<150 μm for 316L and 99%<100 μm for the intermetallic γ-TiAl. This intermetallic is added to the matrix 316L in the proportions of 3, 6 and 9% in volume. Powders were dry mixed in a rotating laboratory mill at 80 rpm for 30 min. Afterwards, they were uniaxially pressed at 700 MPa.