3Optimum Design and Fabrication of TiC/NiAl-Ni Functionally Graded Materials

Abstract

In recent years functionally graded materials(FGMs) have received considerable attention. Ceramic/metal type FGMs are believed to be hold promise in applications for advanced technology, especially in aerospace and nuclear engineering, where the materials encounter high heat loads. On the basis of the traditional cermet TiC-Ni, TiC/NiaAl-Ni FGM system was taken, which was composed of Ni as the metal phase, TiC as the ceramic phase and TiC-Ni3Al composites with various Ni3Al ( has a lower thermal expansion coefficient and a better wettability with TiC ) volume fraction as the graded interlayers. TiC/Ni3Al-Ni system was chosen for the potential use as the first wall materials of thermonuclear experimental reactors. The residual thermal stresses during fabrication were calculated by finite element method. Based on the consideration of minimum stress, minimum ratio of stress to fracture strength and proper distribution of thermal stress in pure TiC side, the optimum design with the distribution exponent P=1.6 was reached. According to the design result, TiC/Ni3Al-Ni FGM samples were then successfully fabricated.