Phase Transformation in Mechanically Alloyed and Hot-Pressed Nb-4Si-8B and Nb-8Si-16B Alloys

Abstract:

The work reports on the phase transformation in mechanically alloyed and hot-pressed Nb-4Si-8B and Nb-8Si-16B (at-%) alloys. Elemental powder mixtures were processed in a planetary ball mill under argon atmosphere using 300 rpm, stainless steel balls (19 mm diameter) and vials (225 mL), and a ball-to-powder weight ratio of 10:1. After dry milling for 7h, wet milling with isopropyl alcohol for more 20 min was adopted to increase the recovering of previously cold-welded Nb-4Si-8B powders. To obtain the equilibrium structures the as-milled powders were hot-pressed under vacuum at 1200^oC for 1 h. The as-milled powders and hot-pressed samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. XRD results revealed the presence of metastable phases in as-milled Nb-Si-B powders. The hot pressing has produced dense Nb-Si-B samples, which were formed by the Nbss, Nb₃B₂ and Fe₂Nb phases beside of other unknown Si-rich phase.

• Periodical: Materials Science Forum (Volume 802)
• Pages: 14-19
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.802.14
• Online since: December 2014
• Authors: Carlos Edilson Chiaradia*, Luciano Braga Alkmin, Carlos Ângelo Nunes, Vinícius André Rodrigues Henriques, Gilda Maria Cortez Pereira, Alfeu Saraiva Ramos
• Keywords: Contamination, High-Energy Ball Milling, Hot Pressing, Niobium Alloys

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