Low Pressure Induction Plasma Spraying of Titanium Metal Matrix Composites SCS-6/Ti6Al-4V and SCS-6/Ti6Al-2Sn-4Zr-2Mo

Abstract

Two titanium metal matrix composites (MMC's) have been successfully fabricated from low pressure induction plasma sprayed monotape and their mechanical behavior has been characterized. Powders of Ti6Al-4V (Ti6–4) and Ti6Al-2Sn-4Zr-2Mo (Ti6-2-4-2) were used as matrix sources and the reinforcement was Textron Specialty Materials (TSM) SCS-6 silicon carbide fiber. The importance of process control to minimize interstitial (O, N, H and C) contamination effects is discussed. Oxygen pick-ups were reduced to typically less than 200 ppm and total interstitial pick-up levels were in the range of 200–500 ppm. Uniaxially reinforced composite panels of 4-ply construction were fabricated from these monotape materials by the HIP process and tension tests in the fiber direction were performed. Tensile strengths and elastic moduli averaged 1565 MPa (227 KSI) and 182 GPa (26.4 MSI) for the SCS-6/Ti6-4; and 1531 MPa (222 KSI) and 184 GPa (26.7 MSI) for the SCS-6/Ti6-2-4-2 for composite fiber volume fractions of 0.27 – 0.28 and 0.29 – 0.30, respectively. The results compared favorably with other fabrication approaches for these composite systems and with rule-of-mixture (ROM) predictions. It was concluded that SCS-6/titanium composites fabricated from plasma sprayed monotapes exhibit properties consistent with state-of-the-art MMC fabrication technology.