Mechanical properties and thermal shock resistance of tungsten alloys strengthened by laser fragmentation-processed zirconium carbide nanoparticles

Abstract

Zirconium carbide (ZrC) nanoparticles with an average size of 5.6 nm were synthesized through laser fragmentation (LF) from as-received 20–60 nm ZrC particles, and LF-ZrC nanoparticle dispersion-strengthened tungsten (LF-WZC) samples were fabricated by spark plasma sintering method. The average grain size of LF-WZC is 1.91 μm and most ZrC particles in LF-WZC are smaller than 10 nm. LF-WZC exhibits finer grain size, higher yield strength and hardness but lower ductility as compared with W-ZrC samples using as-received ZrC (WZC). The results showed that finer ZrC nanoparticles dispersed in tungsten can enhance the strength by hindering the motion of dislocations, but they may also introduce stress concentration and thus reduce the ductility. The thermal shock resistance of the WZC and LF-WZC samples was investigated using an electron beam device. The LF-WZC sample also exhibits a higher cracking threshold (0.33–0.44 GW·m−2) than WZC (0.22–0.33 GW·m−2) at room temperature. The enhanced thermal shock resistance of LF-WZC could be attributed to its high yield strength.