Effects of boron content on environmental embrittlement of ordered Ni3Fe alloys

The effects of boron content (CB = 0–0.14% (mass fraction)) on the tensile properties and environmental embrittlement of ordered Ni-24%Fe (atom fraction)-B (Ni3Fe-B) alloys have been investigated using tensile tests in vacuum and under gaseous hydrogen. The results indicate that, when CB < 0.06% (mass fraction), the tensile strength and elongation of the alloys in vacuum and gaseous hydrogen increase as CB in the ordered Ni3Fe-B alloy increases. The tensile strength and elongation are maximum, and the hydrogen embrittlement factor (IH) is minimum for the ordered Ni3Fe-0.06%B (mass fraction) alloy. Compared with the ordered B-free Ni3Fe alloy, IH of the ordered Ni3Fe-0.06%B (mass fraction) alloy decreases by 98.1%, and the fracture morphology of the alloy changes from fully intergranular to fully transgranular, when tested in gaseous hydrogen. A critical level of boron segregation at the grain boundaries of ordered Ni3Fe-B alloys is observed. The hydrogen embrittlement of ordered Ni3Fe-B alloys in gaseous hydrogen can be completely suppressed by boron atoms when CB ⩾\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\geqslant$$\end{document} 0.06% (mass fraction).