Tensile, creep and fracture testing of prospective Fe-Al-based alloys using miniature specimens

摘要

Mechanical properties of prospective Fe-Al- based alloys were investigated using miniature specimens. This enables testing of material from experimental heats that did not allow preparation of standard specimens. Small punch test and mini-tensile test were applied for estimation of the mechanical properties of Fe-22 Al and Fe-22Al-7Ti (at.%) at high temperatures. It is shown that the force applied in the small punch test can be successfully converted into the equivalent applied stress using the empirical formula suggested by the new European standard for small punch testing. The minimum deflection rate can be converted into the minimum creep strain rate as well. The improvement of the latter conversion based on the Monlanan-Grant relationship is proposed. The small punch testing enables evaluation of rupture properties including the creep rupture strength. This can effectively complement previous investigations of Fe-Al-Ti alloys performed predominantly in uniaxial compression. It is shown that a significant increase in creep resistance is achieved by addition of titanium and a two-phase microstructure analogical to that in gamma'-strengthened nickel-based superalloys is observed.