Multi-temperature uniaxial compression testing of sintered ZrN and (Zr,Ti)N pellets as surrogates for PuN and (Pu,Zr)N fuels

In this work, ZrN and (Zr,Ti)N were studied as possible surrogates for PuN and (Pu,Zr)N. The mechanical properties of sintered ZrN and (Zr,Ti)N pellets were examined to investigate the effects that sintering temperatures and composition have on structural integrity. Uniaxial compression testing was performed on ZrN and (Zr,Ti)N pellets sintered at either 1375°C 1475°C or 1600°C. Testing was performed in an ultra-high purity Argon atmosphere at two temperatures: 25°C and 800°C. Post-Mortem fractography was performed using scanning electron microscopy (SEM). In most cases elevated temperature testing resulted in a reduction in compression strength by nearly 50%, an increase in compressive strain and an introduction of non-critical cracking prior to catastrophic failure as compared to 'identical' samples tested at room temperature. It was determined that (Zr,Ti)N solid solution samples have similar or higher specific strength (strength divided by density) when tested at intermediate temperatures as compared to pure ZrN samples due to their smaller grain size, higher porosity, and because of increased crack arrest mechanisms and elastic energy dissipation sites. It is believed that the strength and fracture behavior of these solid solution samples would be desirable in a multi-element transmutation fuels application. Work supported under the Global Nuclear Energy Partnership (GNEP) and the Advanced Fuel Cycle Initiative (AFCI), DOE/NE Agreement # DE-FC07-05ID14654.