Fabrication of Al matrix in situ composites via self-propagating synthesis

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 1994-11, Vol.187 (2), p.189-199
• Main Authors: Gotman, I., Koczak, M.J., Shtessel, E.
• Format: Article
• Language: English
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/0921-5093(94)90347-6

Al matrix composite materials with 30 vol.% TiC, TiB 2 and TiC + TiB 2 ceramic reinforcements were processed in situ via self-propagating high temperature synthesis (SHS) followed by high pressure consolidation to full density. Non-steady-state oscillatory motion of the combustion wave was observed during the SHS processing, resulting in a typical layered structure of the reaction products. The microstructure and phase composition of the materials obtained were studied using X-ray diffraction, optical microscopy and scanning (SEM) and transmission (TEM) electron microscopy. Very-fine-scale ceramic particles ranging from tens of nanometers up to 1–2 μm were obtained in the Al matrix. Microstructural analysis of the reaction products showed that the TiB 2/Al and (TiB 2 + TiC)/Al composites contained the Al 3Ti phase, indicating that full conversion of Ti had not been achieved. In the TiC/Al composite a certain amount of Al 4C 3 was detected. High room and elevated temperature mechanical properties (yield stress, microhardness) were obtained in the high-pressure-consolidated SHS-processed TiC/Al and TiB 2/Al composites, comparable with the best rapidly solidified Al-base alloys. These high properties were attributed to the high density of the nanoscale ceramic particles and matrix grain refinement.