Designing and manufacturing of functional diffusive machine and its performance evaluation in the fabrication of Al-Al2O3 samples

In this paper, a novel fabrication technique for functionally graded materials (FGMs) to have a programmed and continuous material pouring is presented. Microscopic examination and studying the desired gradient in various samples as well as studying the effects of volume fraction of constituents on microstructure, relative density and micro-hardness of the samples are other investigations presented in this article. The fabricated samples are made of Al powder as the matrix and Alumina (Al2O3) ceramic particles as the reinforcement. Functional gradient of Alumina particles distribution in the Al matrix along a cylindrical sample was applied using a novel material pouring device. After pouring the powder mixture with 10, 15, and 20 vol% of reinforcement into the die, various compacting pressures of 100, 200, 400, and 500 MPa were applied to the sample and sintering process under 700 oC temperature was carried out. The results show acceptable accuracy of the material pouring device after examining the distribution of reinforced particles. As well, it is obtained that as the volume fraction of Alumina particles increase, the relative density decreases and the Vickers micro-hardness enhances. So that, the most hardness in 20% Alumina sample is observed about 95.8 HV. In addition, as the compacting pressure increases, the relative density enhances up to 96%. In Al-15 vol% Al2O3 sample, increasing the compacting pressure from 200 to 500 MPa caused an improvement in micro-hardness by about 200%.