Elastic softening via crystallographic texture: Decoupling grain size, shape, and orientation effects in phase-transforming polycrystals

The elastic softening of polycrystalline phase-transforming materials (PTMs) is intricately linked to their microstructural characteristics, yet the individual and coupled roles of grain size, shape, and orientation remain inadequately resolved. Here we employed 3D phase-field simulations on an iron-nickel alloy with strong elastic anisotropy to decouple these effects. It was demonstrated that crystallographic texture dominates elastic softening, reducing the modulus by up to 75 % when grains align along soft crystallographic orientations. Grain size exerts negligible influence on the elastic modulus of coarse- and fine-grained PTMs under small loads but critically governs phase transition hysteresis under large deformation. Morphological anisotropy introduced by elongated or flattened geometries of grains modifies the modulus by ∼10 %. Nonlinear interactions between texture and grain morphology further modulate softening magnitudes, deviating from linear superposition predictions. By decoupling these effects, it is suggested that texture engineering via orientation alignment is the most effective pathway for designing PTMs with tailored elastic softening. This work provides a microstructure-property map for designing PTMs with desired elasticity.