Modelling of microstructure evolution during laser processing of intermetallic containing ni-al alloys

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

Frontiers of Nanoscience

Antimicrobial coatings are a promising strategy to counteract the spreading of multidrug resistant pathogens through cross-contamination of surfaces. Coatings with nanostructured characteristics can exploit the different antimicrobial mechanisms of nanomaterials if the synthesis methods are able to tune the composition, morphology, and mechanical properties of the film. This chapter addresses the synthesis of antibacterial nanostructured coatings with a focus on physical synthesis methods. After a short description of the bacteria-NP interaction mechanism leading to killing of the cells, few examples of coatings obtained by magnetron sputtering and supersonic cluster beam deposition are discussed, with an emphasis on the possibility of combining different elements into the coating to widen the bactericidal spectrum