Nickel_-hexagonal phase induced in Ni₃Si_-monoclinic intermetallic phase by ion beam irradiation

Abstract

A hypereutectic Ni alloy with 22 at. % Si was irradiated with a high-energy nickel ion beam and high ion fluence at 650°C to induce the formation of intrinsic and extrinsic point defects. Under these irradiation conditions, high concentrations of point defects were formed in the irradiated region. The recovery process initiated due to the damage induced by irradiation led to the formation of a nanoparticle population in the irradiated region. The irradiated region was characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The experimental evidence obtained permitted the establishment of an event sequence that culminated in nanoparticle population formation. The event sequence had the following stages: (a) Ni atom population implantation within a specific zone of the irradiated region; (b) nucleation and growth of a Nickel_-hexagonal phase due to ordering of the implanted nickel atoms; and (c) Ni_-hexagonal phase nanoparticle growth within a specific region of the irradiated region. The HRTEM analysis yielded crucial insights into the mechanisms underlying nanoparticle formation. The two most important aspects are as follows: firstly, the nucleation of Nickel_-hexagonal phase into an amorphous region, and secondly, the non-equilibrium nature of the Nickel_-hexagonal phase of the Nickel metallic system. These experimental findings are important for implantation technology; implanting atomic species into certain materials to create composite materials can lead to the formation of non-equilibrium phases and amorphous regions. Both of these outcomes have the potential to adversely affect the properties of the composite material.

KEYWORDS:

• Ni-hexagonal phase
• nanoparticles
• interaction
• dislocation lines
• ion implantation
• intermetallic phase

Acknowledgments

The authors thank the tandem accelerator staff at the Solid-State Research Institute, Forschungszentrum (FZ), Jülich, Germany. AGB thanks the support of FZ-Jülich and Dr. W. Kesternich for their fruitful discussions during the irradiation experiments.

Disclosure statement

No potential conflict of interest was reported by the author(s).