Effect of nanometric oxide dispersion on creep resistance of ODS-FeAl prepared by mechanical alloying

Abstract

The aim of this work was to analyse the influence of nanometric ceramic dispersion on the high temperature mechanical properties (referred hereafter as mechanical properties) of oxide dispersion strengthened FeAl intermetallic (ODS-FeAl). This material has been prepared by mechanical alloying (MA) of elemental Fe and Al powders and subsequent sintering. The dispersion was introduced by in situ oxidation during the MA process. It was found that sintering must be performed at low temperature (1050 °C) and in these conditions results in a suitable nanosized FeAl2O4 dispersion (15 nm) within a submicronic FeAl matrix. The mechanical properties of this material have been analysed in constant velocity compression tests at 727 °C, as a function of processing parameters. In optimised sintering conditions, ODS-FeAl shows a threefold increase in the reference flow stress (σ = 347 MPa atdϵd = 3.3 10−5 s−1and T = 727 °C) and high stress exponent (n = 13), as compared to the reactively sintered FeAl tested in the same conditions (σ = 104 MPa, n = 6.5). The stability of nanometric dispersion and mechanical properties were confirmed by 1000 h, heat treatment at 700 °C. The mechanical properties of FeAlFeAl2O4 composite are compared with some reference materials, including commercially available stainless steels and Inconel 625 superalloy.