Influence of particle dispersions on the high-temperature strength of ferritic alloys

Four ferritic alloys based on the composition Fe–14Cr–3W–0.4Ti (nominal wt%) were developed with a predominant dispersion of either oxide particles or nano-size Y-, Ti-, O-rich clusters, or nanoclusters (NC). Tensile specimens machined from the alloys were tested at room temperature and at temperatures ranging from ∼360 °C to 800 °C in air using a strain rate of 10−3 s−1. The results showed that the high-temperature strength of the NC strengthened alloys was significantly better than that of the oxide strengthened alloys. The room temperature yield strengths of the two alloys containing the NC were 1469 MPa and 1261 MPa while the yield strengths of the two oxide dispersion alloys were 819 MPa (Y–Ti-oxides) and 583 MPa (Ti-oxides). However, the ductility of the oxide strengthened alloys was better than that of the NC strengthened alloys.