Structural mechanisms of enhanced mechanical properties in amorphous- nanocrystalline ZrCu alloys under irradiation

ZY Gan and PW Wang and MF Li and YH Zhou and B Malomo and L Yang, JOURNAL OF MATERIALS SCIENCE, 58, 5061-5071 (2023).

DOI: 10.1007/s10853-023-08340-7

This study investigates the tensile deformation behavior of irradiated ZrCu amorphous-nanocrystalline (ANA) alloy with a view to capturing essential mechanisms for mechanical performance. Amorphous models of as- constructed metallic glass (MG), as-constructed ANA and irradiated ANA were synthesized and evaluated by molecular dynamics MD simulations. In the ANA models, effective stress activations energized local regions to stimulate a maze of shear transformation zones (STZs) at the interfaces due to the precipitation of Zr2Cu nanocrystal grains. The distinction in the formation and propagation of shear bands in as-constructed MG and ANA models is evidenced by the unusual distribution of STZs in the latter, as multiple shear bands were compelled to traverse specific orientations in their MG matrices with a beneficial structural effect. Shear band strengths predicated on quasi-steady stress evolution indicated a superior mechanical performance of the ANA models because fewer free volumes were sufficient to restrict the propagation of shear bands. As mature shear bands propagating in misaligned 45 degrees and 135 degrees directions intersected and were arrested at the ANA interface, an exclusive plasticity-enhanced effect was induced in the as-constructed ANA model. Remarkably, the transection of the MG matrix by shear bands at 45 degrees and 135 degrees in the irradiated ANA model surprisingly induced a cross-blocking effect by competitive shear band growth with a rise of free volumes, as multiple shear bands retarded propagation in parallel orientations to evolve a phenomenal plasticity- enhanced performance. Effectively, the correlation between irradiation- induced structural mechanisms, unique shear band performances and mechanical behavior is therefore established as a pathway to developing advanced materials with excellent mechanical performance.

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