Theoretical and Experimental Studies of the Structural, Phase Stability and Elastic Properties of AlCrTiFeNi Multi-Principle Element Alloy

Abstract

The fundamental challenge for creating the crystal structure model used in a multi-principle element design is the ideal combination of atom components, structural stability, and deformation behavior. However, most of the multi-principle element alloys contain expensive metallic and rare earth elements, which could limit their applicability. Here, a novel design of low-cost AlCrTiFeNi multi-principle element alloy is presented to study the relationship of structure, deformation behavior, and micro-mechanism. This structured prediction of single-phase AlCrTiFeNi by the atomic-size difference, mixing enthalpy ΔHmix and valence electron concentration (VEC), indicate that we can choose the bcc-structured solid solution to design the AlCrTiFeNi multi-principle element alloy. Structural stability prediction by density functional theory calculations (DFT) of single phases has verified that the most advantageous atom occupancy position is (FeCrNi)(AlFeTi). The experimental results showed that the structure of AlCrTiFeNi multi-principle element alloy is bcc1 + bcc2 + L12 phases, which we propose as the fundamental reason for the high strength. Our findings provide a new route by which to design and obtain multi-principle element alloys with targeted properties based on the theoretical predictions, first-principles calculations, and experimental verification.

A Unique Quenching and Deformation Dilatometer for Combined In Situ Neutron Diffraction Analysis of Engineering Materials

“…[43] Unfortunately, previous studies have shown that results from Thermo-Calc calculations, such as, for example, phase compositions, phase transformation temperature, and chemical compositions of phases differ to some extent from experiment results. [44][45][46] However, combining dilatometry measurements with in situ neutron diffraction data, the phase transformation type and transformation temperature of HEAs can be determined conveniently from an analysis of the length change signal from dilatometry, and the integrated peak intensity and peak position change from in situ neutron diffraction measurements. Thus, an approach using thermodynamic calculations with combined neutron diffraction and dilatometry can substantially reduce the efforts in the development of new HEA systems.…”

“…The difference between the experiment and the calculated phase diagram has been further confirmed by other experimental results. [45] In addition to predicting the possible phase compositions, Thermo-Calc also provides additional thermodynamic information on the AlCrFeNiTi alloying system as follows: 1) The amount of phase fcc-L12#2 starts to decrease gradually at 750 C until it Reproduced under terms of the CC-BY license. [38] Copyright 2019, The Authors, published by JOM.…”

“…The difference between the experiment and the calculated phase diagram has been further confirmed by other experimental results. [ 45 ]…”