A study on the sintering of ultrafine grained tungsten with Ti-based additives. (June 2017)

• Record Type: Journal Article
• Authors: Ren, Chai; Koopman, Mark; Zak Fang, Z.; Zhang, Huan; van Devener, Brian
• Is Part Of: International journal of refractory metals & hard materials. Volume 65(2017)
• Page Start: 2
• Page End: 8
• Publication Date: 2017-06
• Subjects: Nanocrystalline material -- Tungsten -- Titanium -- Sintering -- Grain growth -- Ultrafine grain; 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.2016.11.013
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: Tungsten (W) is a brittle material at room temperature making it very difficult to fabricate. Although the lack of ductility remains a difficult challenge, nano-sized and ultrafine grain (UFG) microstructures offer potential for overcoming tungsten's room temperature brittleness. One way to manufacture UFG W is to compact and sinter nanosized W powder, however, it is a non-trivial task to control grain growth during sintering. In an effort to inhibit grain growth, the effect of Ti-based additives on the densification and grain growth of nano-W powders was investigated in this study. The addition of 1 wt.% Ti into tungsten led to more than a 63% decrease in average grain size of sintered samples at comparable density levels. It was also found that sintering in Ar yielded a finer grain size than sintering in H2 at similar densities. Compared to conventional high temperature sintering, a lower temperature sintering cycle for a longer hold time resulted in both near-full density and fine grain size. The roles of the Ti additive include not only the inhibition of grain growth, but also the potential absorption of oxygen from W particles. Highlights: Addition of minor amounts of Ti led to a dramatic decrease in grain size of sintered W Sintering for long hold times at low temperature resulted in near-full density and fine grain size. The Ti additive functioned as a grain growth inhibitor. Ti addition may absorb oxygen from adjacent W grains or grain boundaries.