Combustion synthesis of (Mo_(1-x)Cr_x)Si2 (x = 0.00-0.30) alloys in SHS mode

摘要

Combustion synthesis was adopted to successfully synthesize molybdenum-silicon-chromium (Mo-Si-Cr) alloys by the mode of self-propagating high-temperature synthesis (SHS). The experimental study of combustion synthesis of Mo-Si-Cr alloys was conducted on elemental powder compacts. Powder compacts with nominal compositions including MoSi2, (Mo_(0.95)Cr_(0.05))Si2, (Mo_(0.90)Cr_(0.10))Si2. (Mo_(0.85)Cr_(0.15))Si2, (Mo_(0.80)Cr_(0.20))Si2, (Mo_(0.75)Cr_(0.25))Si2 and (Mo_(0.70)Cr_(0.30))Si2 were employed in combustion synthesis experiments. The combustion mode, combustion temperature, flame-front propagation velocity and product structure were investigated. The results showed that Mo-Si-Cr alloys were synthesized by an unsteady state combustion mode with a spiral-trajectory reaction front. The peak combustion temperature reduced with the addition of Cr to Mo-Si system. The flame-front propagation velocity decreased with an increase in Cr content of the powder compact. The X-ray diffraction (XRD) results showed that the crystal structure of the combustion product changed from Cll_b-type structure (Mo_(0.90)Cr_(0.10))Si2 to C40-type structure (Mo_(0.85)Cr_(0.15))Si2 with increase in Cr content of Mo-Cr-Si alloys. The intensities of diffraction peaks of the C40-type phase gradually increased with increase in Cr content.