EFFECT OF NANOMETRIC OXIDE DISPERSION ON CREEP RESISTANCE OF ODS-FEALPREPARED BY MECHANICAL ALLOYING

The aim of this work was to analyse the influence of nanometric cerami c dispersion on the high temperature mechanical properties (referred h ereafter as mechanical properties) of oxide dispersion strengthened Fe Al intermetallic (ODS-FeAl). This material has been prepared by mechan ical alloying (MA) of elemental Fe and Al powders and subsequent sinte ring. The dispersion was introduced by in situ oxidation during the MA process. It was found that sintering must be performed at low tempera ture (1050 degrees C) and in these conditions results in a suitable na nosized FeAl2O4 dispersion (15 nm) within a submicronic FeAl matrix. T he mechanical properties of this material have been analysed in consta nt velocity compression tests at 727 degrees C, as a function of proce ssing parameters. In optimised sintering conditions, ODS-FeAl shows a threefold increase in the reference flow stress (sigma = 347 MPa at d epsilon/dt = 3.3 10(-5) s(-1) and T = 727 degrees C) and high stress e xponent (n = 13), as compared to the reactively sintered FeAl tested i n the same conditions (sigma = 104 MPa, n = 6.5). The stability of nan ometric dispersion and mechanical properties were confirmed by 1000 h, heat treatment at 700 degrees C. The mechanical properties of FeAl-Fe Al2O4 composite are compared with some reference materials, including commercially available stainless steels and Inconel 625 superalloy. (C ) 1996 Elsevier Science Ltd.