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Engineering Science in
Additive Manufacturing Multi-material additive manufacturing of metals

techniques, such as near-IR cameras and optical emission A B
spectrometry, to monitor melt pool integrity and surface
finish. Emerging approaches like 3D laser scanning have
also been applied to detect geometric deviations during
builds. C D E

Moreover, current state-of-the-art in-process
monitoring could allow the research community to further
characterize and advance MMAM, which will be further
discussed in Section 6.2. F

3. MM bimetallic interfacial
characterization

The microstructures at the interfaces between dissimilar
materials play a crucial role in dictating the mechanical G H
properties of MMAM components. In the context of
bimetallic structures, the materials involved often possess
similar atomic bonds, as well as comparable physical
and chemical properties, including melting temperature,
CTE, thermal conductivity, and elemental composition.
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Consequently, a fusion region is formed at the interface I J
of dissimilar materials, facilitating the interlocking of
materials and thereby enhancing their metallurgical
bonding strength. Such insights underscore the importance
of understanding and optimizing microstructural
characteristics for the advancement of MMAM.
K
The interfacial microstructure of dissimilar materials L
exhibits varying traits, necessitating a closer examination
of each material’s unique characteristics. This section
explores the microstructural characteristics of significant
bi-metal alloys, namely Ti, SS, Ni, Al, and Cu as base M
materials. Each of these alloys presents distinctive
interfacial characteristics influenced by factors such
as composition, crystalline structure, and processing
conditions. Understanding these nuances is crucial
for optimizing MMAM process parameter selection
and improving the mechanical properties of MMAM
structures. Each subsection is focused on one base material
alloy and contains a description of the relevant available
literature.
Figure 4. Interfacial meso- and microstructural characteristics of
3.1. Stainless steel-based bimetallic alloys stainless steel and nickel-based bimetallic alloys fabricated through
different multi-material (MM) additive manufacturing techniques.
Understanding the bonding between SS and Ni has been (A and B) SS316/IN625 produced by MM-laser powder bed fusion
explored numerous times (Table 1), with a few examples (LPBF). Scale bar: 1 mm. Reprinted with permission from Bodner et al.
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shown in Figure 4. This combination of alloys is relevant Copyright © 2020, Elsevier B.V. (C-F) SS316/IN625 MM-laser-directed
energy deposition (LDED). Scale bars: 1 mm and 250 μm. Reprinted
in extreme applications, including nuclear and aerospace, with permission from Chen et al. Copyright © 2020, Elsevier B.V. (G-J)
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where properties such as high strength, corrosion and SS316L/IN718 MM-LPBF and (K-M) SS316L/IN718 MM-LDED .
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oxidation resistance, creep, and fatigue resistance are Scale bars: 5 μm, 10 μm, 25 μm, 100 μm, 200 μm and 250 μm. Reprinted
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required. 156,180 In the work by Bodner et al., SS316L/ with permission from Yusuf et al. Copyright © 2020, Elsevier B.V. and
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IN625 bimetallic structures were fabricated using liquid- Ghanavati et al. The images highlight significant characteristics of the
interfacial morphology, phase transformation, grain structure, growth,
dispersed metal powder bed fusion. Due to the residual and bonding quality influenced by the process techniques and material
stress gradient at the interface, a zigzag-patterned crack combinations.
Volume 1 Issue 2 (2025) 9 doi: 10.36922/ESAM025180010