Junsheng LU Baorong WU Dept.of Alloy Steel
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Central Iron and Steel Research Institute Beijing
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100081
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ChinaG.J.Wang Dept.of Materials Science and Engineering
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University of Pennsylvania
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Philadelphia
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PA 19104
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USA
材料科学技术（英文）
The mathematical expressions for magnetomechanical damping capacity are presented by applying Smith-Birchak's model in torsion pendulum and cantilever beam.The peak value ψ_p is found to be related to physical parameters and material constants in the form Kλ_s=αψ_pε_p.which can be used to estimate the magnetostrictive constant λ_s from the damping capacity-strain amplitude curve.A good agreement of experimental data and theoretical prediction was observed in HIDAMETS Cr15A13NiCu.
关键词:
magnetomechanical damping
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N.S.Stoloff Department of Materials Engineering
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Rensselaer Polytechnic Institute
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Troy
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New York
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USAC.T.Liu Metals and Ceramics Division
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Oak Ridge National Laboratory
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Oak Ridge
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Tennessee
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USA
材料科学技术（英文）
A comprehensive review of low temperature environmental embrittlement in intermetallics is pres- ented. Moisture and hydrogen are shown to severely embrittle many intermetallics, including iron, nickel and titanium aluminides. The roles of composition, microstructure and external test variables are emphasized. Several methods to reduce or avoid embrittlement are described.
关键词:
environmental embrittlement
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F.M.Chu David P.Pope Dept.of Materials Science and Engineering
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University of Pennsylvania
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Philadelphia
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PA 19104
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USA
材料科学技术（英文）
In this paper the geometric description and general theory of mechanical twinning are reviewed, the twins in general lattices and superlattices are summarized, and the kinetic process by which mechanical twins form is revisited. A case study of mechanical twinning of HfV2+Nb, (cubic) Laves phase, is presented and the synchroshear of selected atomic layers is proposed to explain the physical process of twin formation. If the twins form in this way, then long shear vectors and / or atomicshuffles are not really necessary.
关键词:
twin
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R.Gibala H.Chang C.M.Czarnik K.M.Edwards A.Misra Department of Materials Science and Engineering
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University of Michigan
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Ann Arbor
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Michigan 48109-2136
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USA
材料科学技术（英文）
This paper demonstrates that plasticity enhancement processes previously observed in bcc metals and associated with the presence of surface films and precipitates or dispersoids are operative in or- dered intermetallic compounds.' Some specific results are given for NiAl-and MoSi_2-based materials.The plasticity of NiAl and related B2 ordered alloys at room temperature during monotonic deformation can be enhanced by application of surface films such as electroless nickel platings.Sig- nificant effects are also observed during cyclic deformation.The presence of ductile second phases such as fcc γ or the ordered phase γ' introduced by alloying also enhances the plasticity of NiAl. MoSi_2 exhibits similar effects of surface films and second phases,but primarily at elevated tempera- tures,T>900℃.In this paper,we illustrate the effects of ZrO_2 surface films deposited near room temperature and TiC particulate additions introduced by powder processing techniques.In all cases, the plasticity enhancement is associated with enhanced dislocation generation processes under the conditions of constrained deformation at the film-substrate or precipitate/dispersoid-matrix inter- face of the composite system.
关键词:
plasticity
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