Microstructure and mechanical properties of novel ZrB₂-reinforced zirconium alloys

Novel ZrB₂-reinforced zirconium (Zr) alloys with different boron (B) and aluminum (Al) contents were produced by arc-melting technique. Microstructural observation indicated that both the α-lath and the prior-β grain size were significantly refined with increased B content. The thickness of α lath gradually increased with increased solute atom Al content. Compressive test results showed that the modulus and strengths of the alloys improved with increased ZrB₂ and Al contents. The presence of abundant ZrB₂ whiskers and solid solution atom Al were responsible for the increased Young's modulus. The strengthening mechanisms can be attributed to strengthening through load transfer between the ZrB₂ whiskers and Zr matrix, morphological changes in alloys resulting from the formation of ZrB₂ whiskers, and solid-solution strengthening caused by Al addition. Fractography confirmed that ZrB₂ whiskers undertook the load transferred from Zr matrix and that crack sources were primarily generated at ZrB₂ whiskers