Changes in Hydrogen Permeability and Microstructures of Nb-(Ti, Zr)Ni Alloys by Cold Rolling and Annealing

• Published in: MATERIALS TRANSACTIONS Vol. 48; no. 9; pp. 2454 - 2458
• Main Authors: Tang, Huxiang, Ishikawa, Kazuhiro, Aoki, Kiyoshi
• Format: Journal Article
• Language: English
• Published: Sendai The Japan Institute of Metals and Materials 01-09-2007; Japan Science and Technology Agency
• Subjects: Alloys; Annealing; Cold rolling; Ductility tests; Hydrogen embrittlement; hydrogen permeability; Materials substitution; Microstructure; Nb40Ti18Zr12Ni30 alloy membrane; Nickel; Niobium; Permeability; Phase transformations; Reduction; Thickness measurement; Titanium; Vacuum annealing; Zirconium
• ISSN: 1345-9678; 1347-5320; 1347-5320
• DOI: 10.2320/matertrans.MRA2007096

Maximum cold rolling reduction rates of as-cast Nb40Ti30−xZrxNi30 alloys were measured to evaluate ductility by measuring the change in the thickness. 50% or higher reduction rates were obtained for the alloys containing the Zr content of 12 mol% or less, but lower values were obtained for the alloys substituted with more Zr. Changes of hydrogen permeability (Φ) and microstructures of the Nb40Ti18Zr12Ni30 alloy caused by cold-rolling and subsequent vacuum annealing were investigated. Φ of this alloy was reduced to the half of the as-cast one by the 50% reduction rate, but recovered to 3.23×10−8 [molH2m−1 s−1 Pa−0.5], which is 1.13 times higher than that of as-cast one, by a subsequent annealing for 360 ks at 1273 K. Although the eutectic phase disappeared and was replaced by a small spherical (Nb, Ti, Zr) phase embedded in the (Ti, Zr)Ni matrix after rolling and subsequent annealing, these alloys showed good resistance to the hydrogen embrittlement at 523 K or more.