Deformation Behaviour of Iron‐Rich Iron‐Aluminium Alloys with Ternary Transition Metal Additions

Abstract

The hardness and yield stress at room temperature and the brittle-to-ductile transition temperature of Fe-AI alloys with 16 at.% AI, which is in the range of the so-called K-state with possible short-range ordering reactions, and ternary additions of 0.5 and 4 at.% of the transition metals Cr, Mo, Mn, V, Ti and Ni were studied with respect to possible hardening effects of the ternary additions. The addition of Cr, Mo and Mn to the Fe-AI alloys produce solid-solution hardening which corresponds to the hardening effect of AI. Only Ti, V and Ni produce extra hardening effects which cannot be related to solid-solution hardening. This extra hardening is attributed to possible fine NiAI precipitates in the Fe-AI-Ni case and to possible enhanced short-range ordering and/or fine carbide precipitates in the cases of Fe-AI-V and Fe-Ai-Ti.

Iron‐Rich Iron‐Titanium‐Silicon Alloys with Strengthening Intermetallic Laves Phase Precipitates

“…Likewise the alloys with Laves phase contents below 10 vol.% compare favourably with binary single-phase Fe-AI alloys with high Al contents up to 17 % since such Fe-AI alloys show a similar yield stress range and similar temperature ranges for thermally activated softening and brittle-to-ductile transition [31]. Higher yield stresses can be achieved through ternary alloying of such Fe-AI alloys to produce hardening second phases, which, however, decrease the low-temperature deformability and increase the brittle-to-ductile transition temperature [11, 28,32]. This corresponds to the behaviour of the present Fe-Si-Ti alloys with higher volume fractions of Laves phase.…”