Modelling of Microstructure Evolution during Laser Processing of Intermetallic Containing Ni-Al Alloys

Abstract

There is a growing interest in laser melting processes, e.g., for metal additive manufacturing. Modelling and numerical simulation can help to understand and control microstructure evolution in these processes. However, standard methods of microstructure simulation are generally not suited to model the kinetic effects associated with rapid solidification in laser processing, especially for material systems that contain intermetallic phases. In this paper, we present and employ a tailored phase-field model to demonstrate unique features of microstructure evolution in such systems. Initially, the problem of anomalous partitioning during rapid solidification of intermetallics is revisited using the tailored phase-field model, and the model predictions are assessed against the existing experimental data for the B2 phase in the Ni-Al binary system. The model is subsequently combined with a Potts model of grain growth to simulate laser processing of polycrystalline alloys containing intermetallic phases. Examples of simulations are presented for laser processing of a nickel-rich Ni-Al alloy, to demonstrate the application of the method in studying the effect of processing conditions on various microstructural features, such as distribution of intermetallic phases in the melt pool and the heat-affected zone. The computational framework used in this study is envisaged to provide additional insight into the evolution of microstructure in laser processing of industrially relevant materials, e.g., in laser welding or additive manufacturing of Ni-based superalloys.

Multi-Phase-Field Simulation of Non-Equilibrium Solidification in 316L Stainless Steel under Rapid Cooling Condition

“…Lu et al 13) simulated the melting and solidification process of the TiAl6V4 alloy using the phase-field method and examined the relationship between the process parameters, such as the scanning speed, size and shape of the molten pool, porosity formation, and solidification microstructure. Abbareh et al 14) simulated the segregation of solute elements in the laser melting process of NiAl alloys using the phase-field method. They analyzed the segregation patterns that varied with scanning speed and solidification rate.…”