The Avrami Kinetics of Dynamic Recrystallization in Nickel-Niobium Alloys

Abstract:

The flow curves determined on a series of Ni-Nb alloys are analysed. Six alloys containing Ni–0.01, 0.1, 1, 2, 5 and 10 wt. % Nb with pure Ni were tested in torsion at various strain rates within the hot forging temperature range. Under these conditions, large strains were attained, which permitted steady state flow to take place. The double-differentiation method is employed to define the critical strain for the initiation of DRX, leading to the evaluation of the strain hardening and dynamic recovery parameters. The relations obtained are compared to ones determined earlier using a least squares approach. It is shown that the two sets of relations do not differ appreciably. These results are employed to predict the Avrami kinetics of a range of Ni-Nb alloys strained at different temperatures and strain rates. The Avrami time exponents all fall in the range 1.0 to 5.0. The dependence of the time of half-softening, t₅₀, on Nb content, strain rate and temperature is also derived under the same conditions.

• Periodical: Materials Science Forum (Volume 941)
• Pages: 2264-2269
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.941.2264
• Online since: December 2018
• Authors: Nadjoua Matougui*, David Piot, Mohamed Lamine Fares, Frank Montheillet, John Joseph Jonas
• Keywords: Avrami Kinetics, Critical Strain, Dynamic Recrystallization, Nickel Niobium Alloys, THERMOMECHANICAL PROCESSING

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