کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
7988273 | 1515813 | 2018 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Phase stability of a ductile single-phase BCC Hf0.5Nb0.5Ta0.5Ti1.5Zr refractory high-entropy alloy
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
فلزات و آلیاژها
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
High-entropy alloys (HEAs) have attracted much attention since they can possess some unique properties. By adjusting their multi-principal elements, some systems with body centered cubic (BCC) structure could obtain an excellent trade-off of strength and ductility, e.g. recently reported single-phase Hf0.5Nb0.5Ta0.5Ti1.5Zr refractory high-entropy alloy (RHEA). However, researchers found that some HEAs are thermally metastable and could decompose within a certain temperature range. The thermal stability is especially important for RHEAs which are promising for high-temperature applications. Here we evaluated the phase stability of a BCC Hf0.5Nb0.5Ta0.5Ti1.5Zr RHEA after anneals for two weeks at 500-900â¯Â°C. Microstructural analyses, performed using X-ray diffraction, scanning electron microscopy, high-resolution transparent electron microscopy, show that the RHEA is a single-phase solid solution after recrystallization for 3â¯hâ¯at 1000â¯Â°C and remains in this state after a subsequent anneal at 900â¯Â°C for two weeks. However, it is unstable and forms second-phase precipitates at and below 800â¯Â°C. Tiny precipitates on the grain boundaries (GBs) were observed in the sample annealed at 800â¯Â°C. Annealed at 700â¯Â°C, precipitates with BCC structure (termed as BCC2) both on the GBs as chains and at intragranular regions as petaloid morphology are present. After the anneal at 500â¯Â°C, the RHEA decomposes into multi-phase microstructures with different morphologies: lamellar structure close to the GBs composed of BCC1 and BCC2 phases, and convoluted basket-like structure inside grains comprising a third hexagonal close-packed phase precipitates except for both BCC phases. Thus the phase stability of this RHEA should be carefully evaluated for elevated temperature applications.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Intermetallics - Volume 98, July 2018, Pages 79-88
Journal: Intermetallics - Volume 98, July 2018, Pages 79-88
نویسندگان
J.Q. Yao, X.W. Liu, N. Gao, Q.H. Jiang, N. Li, G. Liu, W.B. Zhang, Z.T. Fan,