# Mechanical and Thermodynamic Properties of Al11(Ce, M)3 (M = La, Nd) Phases in Heat-Resistant Aluminum: A First-Principles Calculation Study

## TL;DR

This study uses first-principles calculations to explore how adding La and Nd affects the mechanical and thermodynamic properties of Al11Ce3, aiming to improve heat-resistant aluminum alloys for aerospace applications.

## Contribution

The study introduces a systematic DFT-based analysis of La and Nd doping effects on Al11Ce3, revealing novel insights into alloy strengthening through rare earth microalloying.

## Key findings

- Al11(Ce, La)3 shows the highest shear modulus (47.7 GPa), Vickers hardness (8.54 GPa), and Debye temperature (409 K).
- Synergistic La and Nd doping improves metallicity and ductility while maintaining high stiffness.
- Electronic structure calculations reveal mixed bonding characteristics of Al-RE covalent and metallic bonds.

## Abstract

Aluminum alloys are among the most widely used non-ferrous structural materials in industry, but their insufficient heat resistance severely restricts their application expansion in high-end scenarios, particularly in the aerospace field. As a crucial branch of next-generation heat-resistant aluminum alloys, the Al-Ce series alloys rely on the optimized design of alloying elements to enhance their heat resistance and comprehensive mechanical properties. Based on first-principles calculations using density functional theory (DFT), this study systematically investigated the effects of La and Nd single doping and co-doping on the crystal structure, elastic mechanical properties, lattice dynamics, thermodynamic properties, and electronic structure of the Al11Ce3 phase. The results demonstrate that all five doped phases exhibit dynamic and thermodynamic stabilities; among them, the Al11(Ce, La)3 phase shows the highest shear modulus (47.7 GPa), Vickers hardness (8.54 GPa), and Debye temperature (409 K). Furthermore, the synergistic doping of La and Nd can improve the metallicity and ductility of the alloy while maintaining high stiffness. Calculations on electronic properties further reveal the mixed bonding characteristics of Al-RE covalent bonds and metallic bonds, as well as their intrinsic correlation with mechanical property indicators. Our systematic study based on DFT calculations provides theoretical support for regulating the key strengthening phases of Al-Ce-based heat-resistant alloys through rare earth composite microalloying.