Study and characterization of phase formation and stability in an AlCoCrFeNiB0.1 high entropy alloy

Abstract

High entropy alloys (HEAs) belong to a new class of metallic materials that are usually based on at least five major elements, enabling the formation of multicomponent solid solutions with simple crystalline structures. These alloys have interesting mechanical properties, which have been responsible to capture great part of the attentionof the researchers in this field. However, the development of these alloys is challenging due to the lack of information on phase formation and phase stability of multi-component alloys. Based on this, a "Scientific Initiation" project was originally proposed to study and characterize phase formation in HEAs of the AlxCoCrFeNiBy system, processed under different conditions. After the first year of the Scientific Initiation project, many interesting results were obtained and were presented in the technical reports written by the student. Due to the complexity of the microstructures obtained, a more detailed phase characterization was proposed for the second year of the Scientific Initiation project to understand more fundamentally the effect of boron addition on the solidification sequence and phase equilibrium of these alloys. Among the techniques that are being used, transmission electron microscopy (TEM) is of great importance for the development of the project. The department of Metallurgical & Materials Engineering of Colorado School of Mines, CSM, (Golden, USA) has a unique facility for microscopy analysis and sample preparation, equipped with transmission electron microscopes and a focused ion beam system (FIB), which can be used for very precise TEM-sample preparation. This BEPE-proposal aims for the student to spend a period of 2 months at CSM, under the supervision of Prof. Dr. Michael Kaufman working on sample preparation (by FIB) and TEM analysis of an AlCoCrFeNiB0.1 alloy in the as-cast and annealed conditions. The development of this work would provide a deeper understanding of the solidification sequence and equilibrium of the phases formed in this alloy. (AU)