Phase Diagram Determination for Peritectic Systems
This project addresses the poorly understood peritectic transformation in binary alloy phase diagrams; a transformation critical to industrially important systems (Fe-C, Cu-Sn, Cu-Zn, Al- and Ni-based alloys) yet left unresolved in over a hundred ASM-published diagrams due to its dependence on complex, diffusion-controlled solidification kinetics. Since conventional methods (DTA/DSC, post-mortem XRD and microstructure analysis) can't capture this complexity because they depend on heating/cooling rates and lack real-time insight, the project proposes a new methodology combining isothermal, real-time optical microscopy for precise transformation-temperature measurement with a Bridgman-type directional solidification setup for observing microstructure evolution and phase fractions under a constant temperature gradient. The Bi-In system was chosen as the model system because its low melting point and optically distinguishable phases make it ideal for real-time study, and because the boundaries of its [(In) + L → ε] peritectic region (86.5 wt% In, 93.5 °C) remain unresolved in the literature. The expected outcomes are a clarified Bi-In phase diagram, a generalizable methodology for studying peritectic systems, and reliable data to support the design of Bi-In-based solders and phase-change materials for electronics, energy, defense, and manufacturing applications.
Multiphase Melting Dynamics
Solidification is a phase transformation that takes place during the production of almost any metal. The microstructure obtained by solidification leaves fingerprints on the final product, even when the produced material undergoes various subsequent processes. The resulting microstructures determine, to a large extent, the properties of the material. Hence, solidification physics and dynamics have long been investigated. Recently, with the advent of additive manufacturing (AM) technologies (3D printing), the melting phenomenon was shown to be as important an issue as solidification. While very complex microstructures can be obtained even with the controlled solidification of a homogeneous liquid, it is even more challenging to understand and characterize microstructures obtained from non-homogeneous liquid formed due to melting kinetics and rapid (re)solidification. Moreover, since most of the industrial alloys are multicomponent and multiphase, the microstructures formed by melting/solidification cycles in such materials are even more complex, and they can only be understood from a fundamental science perspective that requires careful experiments performed under microgravity conditions, where uncontrollable parameters are minimized. The aim of the project is to understand the melting dynamics of multiphase materials by conducting systematic and controlled model experiments with a nonlinear physics methodology in order to improve our fundamental understanding of microstructure evolution of AM processed parts. For this purpose, the effects of velocity, temperature gradient, and crystal/crystal interphase anisotropy on melting will be quantitatively determined by directionally melting two-phase and three-phase eutectic alloys. The data obtained from the controlled melting experiments will be used as inputs to the AM models.
Microstructure Evolution in Peritectic Systems
Peritectic reactions play a crucial role in the solidification of many industrial alloys, such as steel, brass, bronze, and aluminum-based alloys, yet they are not as well understood as eutectic and dendritic growth. The complexity of peritectic reactions arises from the wide range of microstructures that can form, depending on factors such as alloy composition, convection, and experimental parameters. These microstructures include planar fronts, coupled growth, bands, islands, and helicoidal patterns. Despite the importance of peritectic reactions, significant gaps exist in our understanding of how these structures evolve. In this project, we aim to address these gaps by conducting real-time directional solidification experiments with peritectic systems.
Bu sayfa Mikroyapı Evrim Laboratuvarı (MEL) tarafından en son 08.09.2026 11:43:48 tarihinde güncellenmiştir.
