http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
The effect of microstructure on creep behavior of a powder metallurgy (PM) beta gamma alloy
D. Y. Seo,T. Sawatzky,H. Saari,김대진,P. Au,석창성 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.7
Pre-alloyed beta gamma titanium aluminide powder with a nominal composition of TiAl- 2Nb-2Mo (G2) is consolidated by hot isostatic pressing. After consolidation, a step cooled heat treatment is performed to homogenize the material and produce a fully lamellar microstructure. Various aging heat treatments are then performed to form interfacial beta phase precipitates along lamellar interfaces. The step cooled heat treatment produces a relatively fine microstructure with an average lamellar grain size of 40 μm. The aging heat treatments generate beta phase precipitates along lamellar grain boundaries as well as along lamellar interfaces, and result in limited lamellar degradation and grain growth. However, coarse intergranular grains consisting of beta and gamma grains form during aging. Constant load tensile creep tests are performed on step cooled heat treated and aged specimens. Primary creep resistance, generally, improves with aging time, even with interfacial precipitation, and the limited lamellar degradation occurs with aging. However, total creep life of aged samples decreases with aging time. The microstructures of the tested specimens are characterized and related to the creep behaviour of the TiAl-2Nb-2Mo alloy in the un-aged and aged conditions.
Strain-Induced Spin States in Atomically Ordered Cobaltites
Choi, Woo Seok,Kwon, Ji-Hwan,Jeen, Hyoungjeen,Hamann-Borrero, Jorge E.,Radi, Abdullah,Macke, Sebastian,Sutarto, Ronny,He, Feizhou,Sawatzky, George A.,Hinkov, Vladimir,Kim, Miyoung,Lee, Ho Nyung American Chemical Society 2012 NANO LETTERS Vol.12 No.9
<P>Epitaxial strain imposed in complex oxide thin films by heteroepitaxy is recognized as a powerful tool for identifying new properties and exploring the vast potential of materials performance. A particular example is LaCoO<SUB>3</SUB>, a zero spin, nonmagnetic material in the bulk, whose strong ferromagnetism in a thin film remains enigmatic despite a decade of intense research. Here, we use scanning transmission electron microscopy complemented by X-ray and optical spectroscopy to study LaCoO<SUB>3</SUB> epitaxial thin films under different strain states. We observed an unconventional strain relaxation behavior resulting in stripe-like, lattice modulated patterns, which did not involve uncontrolled misfit dislocations or other defects. The modulation entails the formation of ferromagnetically ordered sheets comprising intermediate or high spin Co<SUP>3+</SUP>, thus offering an unambiguous description for the exotic magnetism found in epitaxially strained LaCoO<SUB>3</SUB> films. This observation provides a novel route to tailoring the electronic and magnetic properties of functional oxide heterostructures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2012/nalefd.2012.12.issue-9/nl302562f/production/images/medium/nl-2012-02562f_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl302562f'>ACS Electronic Supporting Info</A></P>