Self-propagating high temperature synthesis of MoSi 2 matrix composites

Abstract

MoSi 2 is presently regarded as the most important material for electrical heating and as one with huge potential for high temperature structural uses. MoSi 2 and MoSi 2 matrix composites were prepared by self-propagating high temperature synthesis (SHS). Pure MoSi 2 was obtained and a compound of MoSi 2 and WSi 2 was synthesized in the form of predominant solid solution (Mo, W)Si 2. By adding aluminum of 5.5 at.% to Mo-Si, the crystal structure of MoSi 2 changed into a mixture of tetragonal CII b MoSi 2 and hexagonal C40 Mo(Si, Al) 2. The (Mo, W)Si 2-Mo(Si, Al) 2-W(Si, Al) 2 composite materials were synthesized by adding aluminum of 5.5 at.% to Mo-W-Si. However, if the amount of the added aluminum was not larger than 2.5 at.%, it did not have any significant effect. SHS is an effective technology for synthesis of MoSi 2 and MoSi 2 matrix composites.