Feasibility of using Y2Ti2O7 nanoparticles to fabricate high strength oxide dispersion strengthened Fe–Cr–Al steels

• Published in: Materials & design Vol. 88; pp. 862 - 870
• Main Authors: Liu, Tong, Wang, Linbo, Wang, Chenxi, Shen, Hailong, Zhang, Hongtao
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 25.12.2015
• Subjects: Aluminum; Corrosion resistance; Dispersion hardening alloys; Dispersions; Ferrous alloys; Mechanical properties; ODS ferritic steel; Oxides; Structural steels; Transmission electron microscopy; X-ray photoelectron spectroscopy; Y2Ti2O7 nanoparticles; Yttrium oxide; Mechanical properties; Y2Ti2O7 nanoparticles; ODS ferritic steel; Transmission electron microscopy; X-ray photoelectron spectroscopy
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2015.08.118

Addition of Al can improve the corrosion resistance of oxide dispersion strengthened (ODS) steels. However, Al reacts with Y2O3 to form large Y–Al–O particles in the steels and deteriorates their mechanical properties. Herein, we successfully prepared Y2Ti2O7 nanoparticles (NPs) by the combination of hydrogen plasma-metal reaction (HPMR) and annealing. Y2Ti2O7 NPs with contents of 0.2 or 0.6wt.% were then added into the Fe–14Cr–3Al–2W–0.35Ti (wt.%) steel to substitute the conventional Y2O3 NPs by mechanical alloying (MA). The Y2Ti2O7 NPs transformed into amorphous-like structure after 96h MA. They crystallized with a fine size of 7.4±3.7nm and shared a semi-coherent interface with the matrix after hot isostatic pressing (HIP) of the ODS steel with 0.6wt.% Y2Ti2O7. With the increasing Y2Ti2O7 content from 0.2 to 0.6wt.%, the tensile strength of the ODS steel increased from 1238 to 1296MPa, which was much higher than that (949MPa) of the ODS steel added with Y2O3. The remarkably improved mechanical properties of the Al-containing ODS steels were attributed to the increasing number density of Y2Ti2O7 nanoprecipitates. Our work demonstrates a novel route to fabricate high performance ODS steels with both high mechanical strength and good corrosion resistance. In order to improve the mechanical properties of Fe–Cr–Al ODS steels, Y2Ti2O7 nanoparticles (NPs) were added instead of the conventional Y2O3 NPs. These NPs crystallized with a fine size and shared a semi-coherent interface with the matrix after hot isostatic pressing of the ODS steel. The remarkably improved mechanical properties of the Al-containing ODS steels can be attributed to increasing number density of Y2Ti2O7 nanoprecipitates. [Display omitted] •Y2Ti2O7 nanoparticles were added to strengthen the Fe–Cr–Al steels.•They were semicoherent with the matrix and prevent formation of Y–Al–O particles.•The oxide dispersions in the Fe–Cr–Al steel with 0.6wt.% Y2Ti2O7 were 7.4±3.7nm.•The tensile strength of the Fe–Cr–Al steel with 0.6wt.% Y2Ti2O7 reached 1296MPa.