Effect of the heating rate on the microstructure of a ferritic ODS steel with four oxide formers (Y-Ti-Al-Zr) consolidated by spark plasma sintering (SPS)

JOURNAL OF NUCLEAR MATERIALS

卷:518

Article

Macia, E.¹  Garcia-Junceda, A.²  Serrano, M.³  Hernandez-Mayoral, M.³  Diaz, L. A.⁴  Campos, M.¹ 

[1] Univ Carlos III Madrid, IAAB, Dept Mat Sci & Engn, Av Univ 30, Leganes 28911, Spain

[2] IMDEA Mat Inst, C Eric Kandel 2, Getafe 28906, Spain

[3] CIEMAT, Struct Mat Div, Technol Dept, Avda Complutense 22, E-28040 Madrid, Spain

[4] Ctr Invest Nanomat & Nanotecnol CINN CSIC UNIOVI, Grp Mat Nanocompuetos & Bioinspirados, Av Vega 4-6, El Entrego 33940, Spain

关键词: ODS steel;    Mechanical alloying;    Spark plasma sintering (SPS);    EBSD;    Yield strength model;    Microtensile test;    Small punch test (SP);   

DOI  :  10.1016/j.jnucmat.2019.02.043

来源: Elsevier

【 摘 要 】

The proposed ODS ferritic steel alloyed with (Y-Ti-Zr-Al) was produced by mechanical alloying (MA) and spark plasma sintering (SPS) to obtain a complex nanostructure. To densify the material, a sintering cycle by SPS was performed at 1100 degrees C using fast heating rates (from 100 to 600 degrees C/min). During the attrition of MA powders, the uneven distribution of deformation level and of alloying elements has produced an inhomogeneous recrystallization during the consolidation step. Influence of processing condition was studied by modifying the heating rate of SPS to promote a heterogeneous material with bimodal grain size distribution. The final microstructures were characterized by X-ray diffraction and electron microscopy (SEM and TEM). The mechanical behaviour at R.T. was characterized by means of the Vickers microhardness and micro tensile tests. The good balance obtained between ductility (similar to 22-26%) and yield stress (800-910 MPa) at room temperature is provided by the bimodal grain size distribution. To predict the experimental values depending on the processing conditions, a yield strength model is presented. This model covers the contribution of different strengthening mechanism from solid solution, grain size, dislocation density and oxides precipitation. The model indicates the dislocation density as the major strengthening contribution. In addition, small punch (SP) tests were performed to analyse the response of the material at high temperatures where remarkable properties have been achieved. (C) 2019 Elsevier B.V. All rights reserved.

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