Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7973003 | Materials Science and Engineering: A | 2018 | 24 Pages |
Abstract
Precipitates of the Laves and B2 phases were engineered in a newly-designed advanced ferritic alloy. Under creep test at 650â¯Â°C with 120â¯MPa, the material showed a steady-state minimum creep rate of 1â¯Ãâ¯10â4 hâ1, about one order of magnitude lower than T91. Microstructural characterization of the ferritic alloy revealed primarily ductile and partially brittle fractures after the creep test. Coarse Laves phase (~ 1â¯Âµm) was observed associating with the brittle fracture, resulting in reduced creep ductility. However, fine Laves phase precipitates (~ 100â¯nm) helped the dimple-ductile fracture and strengthened the material through impeding the motion of dislocations and boundaries. Unlike the B2 precipitates remained coherent exerting the classic Orowan bypassing mechanism at the brittle location, some of the B2 precipitates at the ductile location became incoherent and can develop an attractive interaction with dislocations. This coherency change of B2 precipitates, together with the nucleation of ultrafine (~ 40â¯nm) Laves phase precipitates during the creep test, would compensate for the coarsening-induced loss of Orowan strengthening of coherent B2 precipitates.
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Physical Sciences and Engineering
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Authors
Tianyi Chen, Chad M. Parish, Ying Yang, Lizhen Tan,