Effects of oxygen on microstructure and evolution mechanism of body-centred-cubic molybdenum. (February 2022)

• Record Type: Journal Article
• Authors: Xing, Hairui; Hu, Ping; Han, Jiayu; Li, Shilei; Ge, Songwei; Hua, Xingjiang; Hu, Boliang; Yang, Fan; Wang, Kuaishe; Feng, Pengfa
• Is Part Of: International journal of refractory metals & hard materials. Volume 103(2022)
• Publication Date: 2022-02
• Subjects: Molybdenum -- Powder metallurgy -- Oxygen content -- Oxygen existing evolution -- Microstructure -- Microhardness; 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.2021.105747
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: Molybdenum metal have high brittleness and ductile-to-brittle transition temperature (DBTT) due to the existence of interstitial oxygen impurities, so it is of great scientific significance to strictly control and accurately analyze the oxygen content. In this work, the effects of oxygen on microstructure and evolution mechanism of body-centred-cubic metallic molybdenum are studied. The X-Ray diffraction (XRD), oxygen nitrogen analyzer, scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and electron probe micro-analyzer (EPMA) are used to analyze the chemical composition, microstructure, oxygen existence and distribution form. The results demonstrate that MoO specimens with up to 3300 ppm of oxygen content have single-phase body-centered cubic microstructure with no precipitates. When the oxygen content in molybdenum increases from 44 ppm to 2200– 3300 ppm, more oxygen exists in the pores between molybdenum grains, and the fracture mode changes from intergranular fracture to intergranular and transgranular mixed fracture. The microhardness increases with increase of oxygen content. These results provide new ideas for controlling the change trend of oxygen in molybdenum and regulating the properties of molybdenum. Highlights: The molybdenum metal with different levels of oxygen (44–3300 ppm) was designed. The molybdenum metal with different levels of oxygen (44~3300 ppm) was designed. Oxygen was in the form of MoO2 and MoO3 powders and transferred to the pores of sintered molybdenum with oxygen content. Effects of oxygen on microstructure and fracture morphology of molybdenum was studied. The Vickers microhardness, density and grain sizes were related to the oxygen content (oxygen content >40 ppm)