Temperature controlled martensitic phase transformations in a model NiAl alloy

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Fe-Ni invar alloy: an example of fractal decomposition?

The important experimental results of irradiated and unirradiated Ni-Fe alloys and some approaches to explain the various contradictory behaviours are discussed. We outline the known results of the scattering experiments and suggest possible directions for theoretical investigations to explain the decomposition kinetics of the FeNi Invar alloy.Обговорюються важливі експериментальні результати опромінених та не опромінених NiFe-сплавів, а також деякі апроксимації для пояснення різних суперечливих характеристик. Ми підкреслюємо відомі результати, отримані в експериментах з розсіянням, та пропонуємо можливі напрямки для теоретичних досліджень, щоб пояснити кінетику розкладу FeNi ИНВАР сплава.Обсуждаются важные экспериментальные результаты облученных и необлученных Ni-Fe-сплавов, а также некоторые аппроксимации для объяснения различных противоречивых характеристик. Мы подчеркиваем известные результаты, полученные в экспериментах с рассеянием, и предлагаем возможные направления для теоретических исследований, чтобы объяснить кинетики разложения FeNi ИНВАР сплава

Dislocation Loop Formation and Growth under In Situ Laser and/or Electron Irradiation

Vacancies and interstitial atoms are primary lattice (point) defects that cause observable microstructural changes, such as the formation of dislocation loops and voids in crystalline solids. These defects' diffusion properties determine the phase stability and environmental resistibility of macroscopic materials under ambient conditions. Although in situ methods have been proposed for measuring the diffusion energy of point defects, direct measurement has been limited. In this study, we propose an alternative in situ method to measure the activation energy for vacancy migration under laser irradiation using a pulsed laser beam from a laser-equipped high-voltage electron microscope (laser-HVEM). We made in situ observations that revealed the formation and growth of vacancy dislocation loops in an austenitic stainless steel during laser irradiation. These loops continued to grow when thermal annealing was performed after laser irradiation at the same temperature. We anticipate that laser-HVEM will provide a new method for investigating lattice defects

Heterogeneous phase changes in alloys induced by a-thermal transport processes

Various phase changes induced by a thermal transport processes are covered. The non equilibrium conditions lead to an altered phase diagram for binary alloys based on stationary states. Examples are ballistic diffusion, irradiation induced and enhanced atomic transport processes and order disorder transformations. An adequate description of the structure and the kinetics can be found by analytical and computer simulation techniques. The Ginzburg Landau approach, Monte Carlo and molecular dynamic treatments of order fluctuations due to local energy deposition is treated in detail. Special interest is also given to diffusionless phase transformation induced by heat spike production. The various processes are important especially for an application for material modification using energetic ion beams. The theoretical approaches will be illustrated by recent experimental result