| Abstract Scope |
Nuclear fusion and Generation-IV fission reactor designs aim for operating temperatures in the range 500°C–1000°C. This precludes the use of conventional zirconium alloys, due to limited oxidation and creep performance at temperatures >400°C. In this work, the similarity in physical metallurgy between titanium and zirconium is exploited to make high (500°C–800°C) temperature zirconium alloys based on the Zr-Al-Sn-(Si,Cr,V) system, designed by analogy to near-alpha titanium alloys (e.g., Ti-834). Using advanced microscopy and diffraction, microstructures analogous to near-alpha titanium alloys have been demonstrated, specifically a lath grain structure with coherent Zr3Al and incoherent Zr-(Si,Cr,V) based precipitates. A key transformation sequence is described, involving continuous nanoscale precipitation of Zr3Al (D019) in a Zr (HCP) matrix, followed by discontinuous precipitation of Zr3Al (L12). Bending, tensile, and creep tests show greatly improved mechanical performance relative to conventional zirconium alloys. Further work to improve the poor oxidation resistance of Zr-Al based alloys is also discussed. |