Recent advances and perspectives in interface engineering of high-performance alloys

Abstract

High-performance alloys are indispensable in modern engineering because of their exceptional strength, ductility, corrosion resistance, fatigue resistance, and thermal stability, which are all significantly influenced by the alloy interface structures. Despite substantial efforts, a comprehensive overview of interface engineering of high-performance alloys has not been presented so far. In this study, the interfaces in high-performance alloys, particularly grain and phase boundaries, were systematically examined, with emphasis on their crystallographic characteristics and chemical element segregations. The effects of the interfaces on the electrical conductivity, mechanical strength, toughness, hydrogen embrittlement resistance, and thermal stability of the alloys were elucidated. Moreover, correlations among various types of interfaces and advanced experimental and computational techniques were examined using big data analytics, enabling robust design strategies. Challenges currently faced in the field of interface engineering and emerging opportunities in the field are also discussed. The study results would guide the development of next-generation high-performance alloys.

1. Introduction

1. Introduction

High-performance alloys have become essential in various industries, such as aerospace, energy, automotive, and electronics industries, where they are required to reliably perform under extreme conditions [1–3]. The outstanding performance of the alloys is due to the complex interplay of multiple mechanisms, and the role played by interface structures has been identified as the primary determinant [4–14]. Specifically, grain and phase boundaries have been found to strongly affect alloy microstructures, thereby controlling the essential macroscopic alloy properties, such as strength [15–21], ductility [22–25], fatigue resistance [26–28], corrosion resistance [29–34], and thermal stability [35–37]. Ding et al. [38] reported that the distinct chemical boundaries in low-carbon medium-manganese steels refine their martensite–austenite structures, resulting in exceptional strength and adequate ductility. However, despite the widespread recognition of the important role played by rational interface engineering in improving alloy performance, a systematic and comprehensive overview addressing the roles played by various interface types in performance optimization of the alloys is yet to be reported.

From a crystallographic perspective, interface characteristics, including interfacial misorientations, lattice mismatches, coherencies, and orientation relationships, directly influence the plastic deformation mechanisms in alloys, markedly affecting their mechanical properties [39–46]. The misorientation angle and boundary plane orientation in grain boundaries are critical factors that determine the interface energy and mobility of alloys, profoundly affecting the dislocation interactions and boundary sliding [47]. In situ transmission electron microscopy (TEM) revealed that the crystallographic structure of low-angle grain boundaries in titanium modulates its dislocation behavior, thereby enhancing its strength–ductility balance [48]. The coherency and lattice mismatch between adjacent phases of titanium significantly influence its mechanical behavior. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and atom probe tomography (APT) observations of Ni(Al,Fe) maraging steel showed that its minimal lattice misfit enhanced the precipitate density, resulting in a strength of 2.2 GPa and ductility of 8.2% [49]. The distinct crystallographic attributes of grain and phase boundaries underscore their pivotal role in optimizing the performance of alloys used in specific engineering applications.