Some dilatometric observations on the α-β transformation in zirconium- [formula omitted] niobium alloy

• Published in: Journal of the less-common metals 1965-03, Vol.8 (3), p.195-208
• Main Author: Slattery, G.F.
• Format: Article
• Language: English
• ISSN: 0022-5088
• DOI: 10.1016/0022-5088(65)90046-9

The effects of repeated heating and cooling on the dilatometric curves in the region of the α /ai β transformation range have been investigated with particular reference to the effect of oxygen contamination at reduced pressures. Data have been obtained on specimen length changes, instantaneous thermal expansion coefficient, dilation change at transformation and transition temperatures. The Goldschmidt expansion on cooling from just below the (α + β) β transition in a vacuum of 2 × 10 −6 mm Hg is ten times greater than when the specimen is cooled from just above this transition, whilst the final length change is ~1% elongation compared with ~1% contraction in the second case. Repeated α /ai β cycling leads to a reduced dilation change and small specimen elongation. The structural implications are discussed. Oxygen contamination at 3 × 10 −4 mm Hg virtually eliminates the dilation change through transformation. The mechanism of formation of horizontal portions to the cooling curve is discussed and on cooling is attributed to the interaction of the transforming outer layers with the still contracting untransformed β core region. Pressure variations in the range 10 −6-10 −4 mm Hg have an important influence on transition temperatures.