Nickel-induced strengthening of boron-doped FeAl (B2) alloys

The effect of nickel additions on yield stress temperature dependence as well as on deformation mechanisms was investigated for Fe-Al alloys containing 40% Al. A set of different nickel containing alloys (up to 10 at.%), B-doped or B-free, was deformed in compression up to 950 °C. Subsequent dislocation structures were examined. It was shown that the addition of nickel strongly decreases the solid state solubility of boron in FeAl (B2) alloys. On the microscopic scale, nickel was confirmed to clearly decrease the dissociation width of the 〈111〉 superdislocations. From a mechanical point of view, it was shown to induce a large and linear strengthening at low temperatures (<400 °C). Owing to that specific hardening, the yield stress anomaly, usually occurring in such materials, was observed to be blurred out, but was nonetheless revealed by a zero strain rate sensitivity.