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Constitutive Relation of Martensitic Transformation in CuAlNi Based on Atomistic Simulations

Y. ZHEN, Z. LI

Abstract


In this work, atomistic simulations on martensitic transformation in CuAlNi are carried out with a second nearest-neighbor modified embedded atomic method (2NN MEAM). The discontinuous deformation gradients in the twinned martensite are calculated based on the rank-one connection and least square analysis. Due to the shear/shuffle of {110}‹110›, the resultant atomistic transformation strain field shows very fine patterns and is identified as large deformation. The associated Cauchy stress field is calculated using atomistic virial stress from molecular dynamics. Shear components of stress and strain along the martensite twin boundary are retrieved from the thermoelastic MT cycle. Based on temporal and spatial averaging, statistics of shear stress and strain gives a pseudo-elastic micro-scale constitutive relation with a hysteresis for martensitic transformation in CuAlNi. The nonlinear relation obtained can be used to study the transformation dynamics in the continuum scale.

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