Fracture behavior of niobium by hydrogenation and its application for fine powder fabrication

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 37; no. 4; pp. 1301 - 1309
• Main Authors: SEMBOSHI, S, MASAHASHI, N, KONNO, T. J, HANADA, S
• Format: Journal Article
• Language: English
• Published: New York, NY Springer 01.04.2006; Springer Nature B.V
• Subjects: Applied sciences; Exact sciences and technology; Fractures; Hydrogenation; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals; Metals. Metallurgy; Phase transitions; Powder metallurgy; Mechanical properties; Application; Niobium; Rupture; Fine powder
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-006-1082-y

Fracture behavior of pure niobium (Nb) by several hydrogenation procedures has been investigated to elucidate the fundamental mechanisms of hydrogen pulverization, which can then be used to produce fine Nb powders with high purity. Concentric, cracks and microcracks were introduced in recrystallized Nb specimens, leading to pulverization, when they absorb hydrogen enough to form a large volume of the face-centered orthorhombic. beta-NbH phase. This hydride phase exhibits anisotropic expansion of Nb lattice and embrittlement. Thus, the fracture of Nb plates occurs in the following sequence: hydrogen absorption, the formation of the ordered, hydride phase, strain generation arising from the phase transformation, and crack nucleation and propagation. The authors also show that Nb powders less than 1 mm were prepared by hydrogenation and ball-milling at a temperature below 203 K, in which hydrogen was removed by dehydrogenation at above 724, K. Thus, fine and contamination-free Nb powders can be effectively, fabricated by using hydrogenation, ball-milling, and dehydrogenation procedures.