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Influences of different hydride nanoparticles on microstructure and mechanical properties of 14Cr3Al ferritic ODS steels

Kang, Zhanbo, Shen, Hailong, Bai, Zhonglian, Zhao, Haozhi, Liu, Tong
Powder technology 2019 v.343 pp. 137-144
hydrides, hydrogen, microstructure, nanoparticles, powders, pressing, steel, tensile strength, zirconium
In order to suppress the formation of large Y-Al-O particles in the Al-containing oxide dispersion strengthened (ODS) steels, spherical Zr/Hf hydride nanoparticles (NPs) of 21 ± 6 nm and 16 ± 4 nm were prepared by the hydrogen plasma metal reaction (HPMR) method and added as raw particles to produce the ODS Fe-14Cr-3Al-2 W-0.35Y2O3 steels using mechanical alloying (MA) and hot isostatic pressing (HIP). Zr/Hf hydride NPs gave rise to the formation of fine complex oxide NPs, Y4Zr3O12 of 14.2 ± 8.1 nm and Y2Hf2O7 of 9.1 ± 6.9 nm. These oxide NPs were semi-coherent with the matrix, (43¯2¯)Y4Zr3O12//(D = 2.57 × 10−17m2/s)α-Fe, and (D = 1.54 × 10−17m2/s)Y2Hf2O7//(D = 6.25 × 10−12m2/s)α-Fe. With the increasing atomic number of IVB group element (from Ti to Hf), the addition of its hydride NPs can create finer complex oxide nanoparticles in the Al-containing ODS steels and bring about higher mechanical properties. The tensile strength of the 14Cr3Al ODS steel added with 0.1 wt% Hf hydride NPs exhibited a tensile strength of 1067 MPa at 25 °C and 284 MPa at 700 °C, higher than those ODS steels added with 0.1 wt% Zr/Ti hydride NPs. Furthermore, the ODS steel added with Hf hydride showed a large uniform elongation of 11.5% at 25 °C. The addition of Hf hydride NPs is promising to develop high performance Al-containing ODS steels.