Study of microstructure evolution and strengthening mechanisms in novel ZrBeAl alloys

• All specimens are composed of α and Be2Zr phases.
• Lattice parameter changed with adding various Al contents.
• The addition of Be plays a crucial role on the prior-β grain size.
• Compressive strength increased and ductility decreased with adding Be and Al.

In this study, the effects of beryllium (Be) and aluminum (Al) content on the microstructure evolution and strengthening mechanisms of Zr alloys were investigated. X-ray diffraction indicated that with increasing Al content in Zr alloys, the lattice parameter “a” of α-phase decreased and the axial ratio “c/a” increased. Microscopic analysis showed that prior-β grain size was substantially refined by increasing Be content. Scanning electron micrographs of the alloys showed that two types of precipitation of Be2Zr particles were present: (1) precipitation along the prior-β grain boundaries and (2) precipitation in the prior-β grains. An increase of Be2Zr particles and Al strongly affected the mechanical properties of Zr alloys. By increasing the Be2Zr and/or Al content, compressive strength was increased whereas the ductility decreased. The significant improvement in strength has been determined to occur through dispersion strengthening and solid solution strengthening.