ISSN: 0090-3973
Page Count: 9

Influence of Heat Treatment on Structure and Oxidation Behavior of Zr-2.5Nb
Ramanathan, LV
Instituto de Pesquisas Energetícas e Nucleares, C.P. 11049, Cidade Universitaria,

Costa, I
Instituto de Pesquisas Energetícas e Nucleares, C.P. 11049, Cidade Universitaria,

Monteiro, WA
Instituto de Pesquisas Energetícas e Nucleares, C.P. 11049, Cidade Universitaria,

(Received 5 April 1988; accepted 31 October 1988)

Abstract

This paper presents the influence of different heat treatments on the microstructure and isothermal oxidation behavior of Zr-2.5Nb in oxygen. The quenched structure consisted of martensitic α′. Upon tempering the quenched alloy at 500°C for up to 100 h, β^Nb precipitated in the matrix, at twin and α′ needle boundaries. At higher tempering temperatures and after longer periods, Nb-rich β^Zr also precipitated. Specimens slowly cooled from the β-phase showed the least resistance to oxidation. The oxidation behavior also varied with the tempering time and temperature. The increased oxidation rate of specimens tempered at 500°C for 1000 h or at 600°C, as compared to those tempered at 500°C for shorter times, has been attributed to formation of Nb containing oxides on the coalesced Nb-rich precipitates and to cracking.

Keywords:
Zr-2.5Nb, heat treatment, tempering, microstructure, isothermal oxidation, precipitates

Paper ID: JTE11108J
DOI: 10.1520/JTE11108J
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