NiAl形状記憶合金の応力誘起マルテンサイト変態におけるバリアント成長過程の分子動力学シミュレーション

概要

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Shape memory alloy has been attracting because of its unique characteristics such as the shape memory effect and the superelasticity. These behaviors arise from reversible movement of atoms during the martensitic transformation driven by thermomechanical loadings. In the present paper, the molecular dynamics simulation of stress-induced martensitic transformation in a NiAl shape memory alloy is carried out focusing on the relation between the evolution of martensite variant and resulting stress-strain behavior. In order to simulate martensitic transformations and to observe stress-strain relation under combined stress state the Parrinello-Rahman method with periodic boundary conditions is used. Microscopic martensite variants are classified by the relative displacement and the angle between transformation shear planes which is identified by change in lattice parameters. In the present simulation, there exist three types of martensite variant depending on the loading direction. The transformation stress varies with the loading direction. Martensitic transformation under simple shear starts and finishes at higher stress level compared to tension and compression. Martensite finish stress is higher in compression than in tension while there is no significant difference in martensite start stress.
一般社団法人日本機械学会の論文
2009-02-25