Changes in features of invariant plane strain with monoclinic distortion in 18R-type martensitic transformation

Journal Article · Fri Jul 24 04:00:00 EDT 1998 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(98)00091-3· OSTI ID:634673

Lee, E S; Ahn, S ^[1]

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1. Research Inst. of Industrial Science and Technology, Pohang (Korea, Republic of). Advanced Materials Div.

In order to clarify the relationship between the monoclinic distortion and the invariant plane strain in the {beta}-18R martensitic transformation of Cu-based shape memory alloys, analytic solutions for the invariant plane strain have been derived. This involves the coupling of the phenomenological theory of the martensitic crystallography with the monoclinic distortion model for the M18R structure. A higher monoclinic distortion has been found to bring about reduction in the tensile and/or compressive strains along the principal axes, and thus the magnitude of the invariant plane strain is linearly related to the monoclinic distortion. Similarly, a higher monoclinic distortion leads to a decrease in the lattice invariant shear, which can be further reduced by the volumetric contraction due to the transformation. The stacking fault density of the 18R martensite has been found to diminish with increasing monoclinic distortion, and its actual stacking fault density has been calculated to be greater than 1/3 when the volumetric contraction occurs during the martensitic transformation.

• OSTI ID: 634673
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 12 Vol. 46; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
COPPER ALLOYS
CRYSTAL-PHASE TRANSFORMATIONS
MARTENSITE
MATHEMATICAL MODELS
MONOCLINIC LATTICES
SHAPE MEMORY EFFECT
STACKING FAULTS
STRAINS
ZINC ALLOYS