High Temperature Tensile Behavior of A۳۵۶-TiB۲/TiC in-situ Composites

In the present investigation, A۳۵۶-TiB۲/TiC composites with a various weight fractions (۰, ۲.۵, ۵ and ۷.۵%) were synthesized through a K۲TiF۶-KBF۴-Graphite (C) reaction system. Formation of TiB۲ and TiC particulates and their distribution are confirmed by various characterization techniques. The tensile properties such as ultimate strength, yield strength, young's modulus and percentage of elongation in addition to their failure behavior of these composites were studied at ambiance and high temperatures (۱۰۰, ۲۰۰ and ۳۰۰۰C). The increment in the volume fraction of the composite raises the hardness and the enhancement of hardness was reported up to ۴۹% at ۷.۵% reinforced composite due to the strengthening effect. The density and porosity of fabricated composites were investigated. The rise in volume fraction of reinforcement phase declines the density and increase the porosity of composites. Further, the ultimate strength, yield strength, young's modulus is declining by raising the temperature. Result analysis illustrates that the ۷.۵% reinforced composite retaining the ultimate strength up to ۸۴.۴% and the ductility is raised by ۲۷% at ۳۰۰۰C. Yield strength and young's modulus are also retained ۷۴.۳۱% and ۷۱.۰۹% respectively at the similar material and experimental conditions. The fracture surface analysis of the composites illustrates that, the ductile nature of failure appearance microscopically with the formation of fine dimples and voids on fracture surface at elevated temperatures. Cleavage facets and tear crumples observation indicates the brittle kind of failure at the ambient temperature. Findings from the experimental study provide the tensile behavior of the composites at the regular working temperature of the automobile engine piston.

کلیدواژه ها:

A۳۵۶-TiB۲/TiC In-situ composites ، Stir casting ، Mechanical properties ، Fractrographic analysis.