Preparation of nanostructural oxide dispersion strengthened (ODS) Mo alloy by mechanical alloying and spark plasma sintering, and its characterization. (June 2022)

• Record Type: Journal Article
• Authors: Yao, Liying; Gao, Yimin; Li, Yefei; Huang, Xiaoyu; Wang, Yiran; Huang, Yijie
• Is Part Of: International journal of refractory metals & hard materials. Volume 105(2022)
• Publication Date: 2022-06
• Subjects: Oxide dispersion strengthened Mo alloy -- Mechanical alloying -- Sintering -- Y-Zr-O oxide; Heat resistant alloys -- Periodicals; Refractory materials -- Periodicals; Metallography -- Periodicals; Alliages réfractaires -- Périodiques; Matériaux réfractaires -- Périodiques; Métallographie -- Périodiques; Heat resistant alloys; Metallography; Refractory materials; Periodicals; Electronic journals; 669.73
• DOI: 10.1016/j.ijrmhm.2022.105822
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: The nanostructural oxide dispersion strengthened (ODS) Mo alloy was successfully fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). In this study, the MA and SPS conditions were systematically studied, and the characteristics of oxide particles were investigated. The results show that the MA process can refine the powder and promote the dissolution of interstitial atoms, but introduce the ZrO2 and excess O impurities. To recycle ZrO2 impurity as a source of active element Zr for alloy preparation, the content of Zr and O with milling time was quantitatively evaluated. In the SPS process, the precipitation of oxide particles retard the densification of as-MA Mo powders. Based on the calculated linear shrinkage, the densification behavior is controlled by sintering temperature, which is driven by grain boundary or dislocation climbing. A high relative density of 99.28% in ODS Mo alloy is achieved using the optimized MA (250 rpm/18 h) and SPS (1400 °C/5 min) parameters. Additionally, the ultrafine Mo grain structure (300 nm) and uniformly dispersed nanoscale Y-Zr-O oxide particles (20.32 nm) inside grains greatly improve the mechanical properties (569.63 ± 28.08 HV0.3 ) of ODS Mo alloys. Non-stoichiometric Y-Zr-O particles, with different Y/Zr ratios (Y/Zr <1), possess a special fluorite crystal structure. Highlights: The nanostructural ODS Mo alloy with ultrafine Mo grain (300 nm) and nanoscale Y-Zr-O particles (20.32 nm) was fabricated. The MA can refine powders and promote the dissolution of interstitial atoms, but introduce ZrO2 and excess O impurities. The precipitation of oxide particles retard powder densification of as-MA Mo powders. Non-stoichiometric Y-Zr-O particles, with different Y/Zr ratios (Y/Zr < 1), possess a special fluorite crystal structure.