Mixing metals, maximizing performance: recent advances on additive manufacturing of heterogeneous/gradient metallic materials

Imagine a jet engine blade with heat-resistant alloys at the tip, lightweight metals at the base, and a gradient blend in between—each material precisely where it performs best. This is no longer just a design dream.

A new review in the International Journal of Extreme Manufacturing highlights how laser powder bed fusion (LPBF) is growing as the key technology for turning such multi-metal masterpieces into reality.

Unlike conventional single-metal parts, heterogeneous and gradient metallic components combine the strengths of different metals within a single structure. The result is parts that can withstand extreme temperatures, resist corrosion, absorb energy, or endure mechanical stresses far beyond the limits of any single alloy. LPBF, with its laser-guided precision and layer-by-layer approach, makes it possible to tailor both structure and composition at the microscale.

Recent research shows LPBF's growing capability to create layered structures, continuous gradients, and even fully three-dimensional architectures with programmable material variation in all directions. Two main manufacturing strategies are leading this progress: one involves building with a single powder before replacing it with another, while the other pre-arranges different powders in specific patterns on the powder bed before melting. Both methods allow engineers to effectively "design" the material distribution inside the part itself.

One of the greatest technical hurdles lies at the interfaces between dissimilar metals. Mismatches in thermal and mechanical properties can lead to cracks, weak bonds, or residual stresses. Researchers are making headway by optimizing laser parameters and build sequences, introducing graded transition zones, shaping the laser beam to better control melting, overlapping material interfaces, and applying hot isostatic pressing to strengthen bonds.

Some are even designing microscopic mechanical interlocks—hooks and ridges that physically lock materials together. When combined with advanced geometries such as porous lattices, these strategies can enhance strength, control heat flow, and improve energy absorption.

However, industrial-scale adoption remains limited. Designing multi-material parts is still a time-intensive process, often requiring manual segmentation and material assignment. Control software for multi-material LPBF lags behind single-material systems. Cross-contamination between powders can reduce performance, build speeds are slower, and recycling mixed powders—a necessity for cost-effective and sustainable production—remains difficult.

Promising solutions are on the horizon. Automated design tools could streamline model creation, while advanced process simulations may predict defects before they occur. Machine learning could enable real-time quality monitoring. External-field assistance, such as magnetic or ultrasonic energy, might improve bonding at interfaces, and carefully tailored heat treatments could further strengthen them. Standardized testing methods will also be critical for ensuring consistent quality and accelerating industrial acceptance.

If these challenges can be overcome, LPBF will not just produce parts—it will produce engineered performance, enabling customized, multi-functional metallic components for the most demanding applications on Earth and beyond. As one researcher noted, "We're not just printing shapes anymore. We're printing performance."

International Journal of Extreme Manufacturing (IJEM, IF: 21.3) is dedicated to publishing the best advanced manufacturing research with extreme dimensions to address both the fundamental scientific challenges and significant engineering needs.

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