Farzin Arianpour - School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST)
Farhad Golestani Fard - Materials and Metallurgical Engineering, Iran University of Science and Technology (IUST)
HamidReza Rezaie - School of Metallurgy and Material Engineering, Iran University of Science and Technology (IUST)

TaC and HfC are thought to have the highest melting point (~۴۰۰۰°C) among all refractory materials. The binary solid solution of TaC and HfC (Ta۴HfC۵) is also considered as the most refractory material with the melting point over ۴۰۰۰ °C and valuable physical and mechanical properties. The main goal of this work is to fabricate TaC/HfCbased composites which consolidated by means of spark plasma sintering (SPS) with addition of MoSi۲ as sintering aid and carbon nanotubes (CNTs) as reinforcement at ۲۰۰۰ °C. The effects of additives were investigated in terms of densification, mechanical properties, phase and microstructural evolutions. It was demonstrated that the relative density could reach from ۹۴ % TD (for binder less sample) to near ۹۹ % for samples containing additives, respectively. The average Vickers hardness and fracture toughness values were in the range of ۱۶-۱۹ MPa and ۲.۹-۵.۳ MPa.m۱/۲. The samples containing CNTs showed improved fracture toughness and the survivability of CNTs, after spark plasma sintering, was proved by scanning electron microscopy of fractured surfaces in addition to the Raman spectroscopy analysis.

Tantalum carbide, Carbon nanotubes, Sintering, Mechanical properties, Phase evolution