With the increasing demand for structural functionality and lightweight in aerospace and marine engineering fields, a growing requirement has emerged for diversity in material and structural properties. For some aerospace components, different structural parts are required to operate in different environments, and traditional homogeneous materials are inadequate. Especially in extreme service environments, materials and structures must integrate multiple properties to address specific engineering or scientific requirements. For example, the same part may exhibit significantly different thermal, mechanical, acoustic, and electrical properties in different locations. Such material combinations with significant physical differences, including metal-metal, metal-polymer, metal-ceramic, and polymer-ceramic, are referred to as materials with significant differences in their physical properties. Development of such materials is critical for weight reduction, and product performance and reliability improvement. With multi-material laser additive manufacturing science and technology development, it is possible to integrate the preparation of materials and components with significant differences in physical properties.

However, the interface problem that occurs in multi-material laser additive manufactured materials in this specific context is particularly important. The interfacial bonding quality of materials with significant differences in physical properties remains a significant problem. Interface defects, excessive residual stress, and cracking severely limit the multi-material laser additive manufacturing of these types of materials. Therefore, this study reviews research advances in laser additive manufactured multi-materials with significant differences in physical properties, focusing on interface problems, optimization methods, modeling and simulation.

Currently, multi-material laser additive manufacturing technology primarily includes: laser powder bed fusion, laser-directed energy deposition, laser-induced forward transfer, multiphoton fabrication, and hybrid multi-material laser additive manufacturing. In the multi-material laser additive manufacturing process, interface problems arise from laser absorption rate differences, thermophysical properties and brittle phase formation at the interface between materials with significant physical property differences. These issues lead to the formation of defects, cracks and residual stress at the interface during fabrication and may even result in interface material delamination and debonding. Therefore, this study investigates interface problems based on the three aforementioned aspects.

A literature analysis is conducted on interface optimization methods for laser additive manufacturing in this context in terms of process optimization, functional gradient design, and integrated manufacturing systems (Fig.10). These provide methods for achieving high-quality formation of materials with significant differences in physical properties. Process optimization primarily includes: parameter optimization, heat treatment, and laser re-melting. Functional gradient design primarily includes: transition and gradient bonding, and interface structure design. Integrated manufacturing systems primarily includes: laser wavelength selection and multi-energy field hybrids. This study provides a detailed explanation for process optimization and functional gradient design, which are widely used optimization methods. Research progress regarding modeling and simulation of laser additive manufacturing of multi-materials with significant differences in physical properties is expounded. Modeling and simulation are important methods for investigating the influence of material property differences on heterogeneous interface formation. By simulating the effects of laser powder bed additive manufacturing parameters on the thermal behavior of heterogeneous interfaces at both macroscopic and mesoscopic scales, optimization of formation parameters can be achieved.

This study reviews research advances on interfaces in the laser additive manufacturing of multi-materials with significant differences in physical properties. This includes multi-material laser additive manufacturing technologies, interface problems and optimization methods, and modeling and simulation in this specific context. Interface optimization methods are also summarized to identify high-quality heterogeneous material formation and to promote the research and application of multi-material laser additive manufacturing.