Tensile deformation and fracture properties of a 14YWT nanostructured ferritic alloy

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• 作者：M.E. Alam^a ; ^{alam@engineering.ucsb.edu" class="auth_mail" title="E-mail the corresponding author} ; S. Pal^a ; K. Fields^a ; S.A. Maloy^b ; D.T. Hoelzer^c ; G.R. Odette^a
• 关键词：Nanostructured ferritic alloy ; Nano oxide ; Delamination ; Tensile properties ; Fractography
• 刊名：Materials Science & Engineering A
• 出版年：2016
• 出版时间：15 October 2016
• 年：2016
• 卷：675
• 期：Complete
• 页码：437-448
• 全文大小：4957 K

文摘

A new larger heat of a 14YWT nanostructured ferritic alloy (NFA), FCRD NFA-1, was synthesized by ball milling FeO and argon atomized Fe-14Cr-3W-0.4Ti-0.2Y (wt%) powders, followed by hot extrusion, annealing and cross rolling to produce an ≈10 mm-thick plate. NFA-1 contains a bimodal size distribution of pancake-shaped, mostly very fine scale, grains. The as-processed plate also contains a large population of microcracks running parallel to its broad surfaces. The small grains and large concentration of Y–Ti–O nano-oxides (NOs) result in high strength up to 800 °C. The uniform and total elongations range from ≈1–8%, and ≈10–24%, respectively. The strength decreases more rapidly above ≈400 °C and deformation transitions to largely viscoplastic creep by ≈600 °C. While the local fracture mechanism is generally ductile-dimple microvoid nucleation, growth and coalescence, perhaps the most notable feature of tensile deformation behavior of NFA-1 is the occurrence of periodic delamination, manifested as fissures on the fracture surfaces.