Coarsening of Laves phase and creep behaviour of a Re-containing 10% Cr-3% Co-3% W steel

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:812

Article

Fedoseeva, A.¹  Nikitin, I¹  Dudova, N.¹  Kaibyshev, R.¹ 

[1] Belgorod Natl Res Univ, Pobeda 85, Belgorod 308015, Russia

关键词: Steel;    Electron microscopy;    Creep;    Diffusion;    Precipitation;    Laves phase;    Coarsening;   

DOI  :  10.1016/j.msea.2021.141137

来源: Elsevier

【 摘 要 】

The coarsening of Laves phase in a Re-containing 10% Cr-3% Co-3% W steel during both creep and ageing at 923 K was investigated. The depletion of W solutes from the ferrite matrix is accompanied with the precipitation of Laves phase, wherein creep strain accelerates both these processes. The equilibrium W content in the ferritic matrix of 1.24 wt% and the volume fraction of Laves phase of 1.6% is reached after 500 h of creep and 1000 h of ageing. This is related to lower activation energy for W diffusion upon creep testing. The coarsening of Laves phase obeys Ostwald ripening and can be described in terms of Lifshitz-Slyozov-Wagner theory: d4 ? d04 = Kp(t-t0), where Kp = 3.70?3.80 ? 10-11 ?m4 s-1 for both creep and ageing suggesting that the coarsening of these particles should be controlled by grain boundary diffusion. No strain-induced coarsening of Laves phase is observed. Growth of the Laves phase particles located on the lath boundaries and the high-angle boundaries of the blocks, packets and prior austenite grains occurs in independent manner. The Laves phase particles located on the highangle boundaries are susceptible to coarsening that leads to appearance of the particles with dimensions >200 nm. The Laves phase particles located on the lath boundaries dissolve with a low rate. Dense chains of Laves phase on the lath boundaries retain up to high creep time giving a significant contribution to creep behaviour.

【 授权许可】

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