TiC/AZ91D composites fabricated by in situ reactive infiltration process and its tensile deformation
(1. Department of Materials Engineering,
Shenyang Institute of Aeronautical Industrial Engineering, Shenyang 110034, China;
2. School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China;
3. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
Shenyang Institute of Aeronautical Industrial Engineering, Shenyang 110034, China;
2. School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China;
3. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
Abstract: An innovative processing route was adopted to fabricate 42.1%(volume fraction) TiC/AZ91D magnesium matrix composites. The reinforcement TiC was in situ synthesized from elemental powders of Ti and C and the matrix magnesium alloy AZ91D pressurelessly infiltrated into the preform of Ti and C. A comparative tensile deformation tests were conducted on the as-synthesized TiC/AZ91D composites and magnesium alloy AZ91D. The true strain—stress curves were fitted by Hollomon relation and their failure mechanisms were finally analyzed. The results show that the in situ formed TiC can increase the tensile strength, and is especially effective at elevated temperatures. Theoretical calculation of the strain hardening exponent (n) for TiC/AZ91D composites indicates that the n value ranges from 0.71 to 0.82 wh, en tensile deformation was carried out at 423−723 K and shows fracture with brittle characteristic. However, the n value of 0.11−0.32 obtained for the matrix alloy AZ91D shows typical ductile features at elevated temperatures.
Key words: magnesium-matrix composites; TiC/AZ91D; in situ reactive infiltration; tensile deformation; strain hardening; fracture mechanism