Functionally Graded Materials: Fabrication and Mechanical Properties

Functionally graded materials (FGMs) are engineered composites in which the composition or microstructure varies continuously or stepwise across one or more dimensions to achieve spatially tailored properties. By grading the volume fractions of constituent phases, these materials can combine the corrosion resistance of ceramics with the toughness of metals or integrate thermal insulation with structural load-bearing capacity. Advances in powder processing, additive manufacturing and field-driven assembly now permit precise control over gradient profiles, enabling complex geometries and multi-functional performance. Mechanical behaviour in FGMs is governed by local stiffness, strength and thermal expansion that vary with position; design approaches often employ power-law or exponential models to describe property variation. Recent studies have explored the stability and vibration characteristics of graded plates and beams, the optimisation of thermal barrier coatings for high-temperature service and the development of new fabrication routes such as spark plasma sintering and vat photopolymerisation. Applications span aerospace components that require smooth stiffness transitions, biomedical implants that mimic natural tissue gradation and electronic devices with integrated functional layers.

Research from Nature Portfolio

A recently reported graded metal-phosphor composite demonstrates a six-layer gradient between dense copper and doped zinc sulfide, fabricated by a simple powder-layering process. The material exhibits stable photoluminescence across a wide temperature range and displays diode-like electrical behaviour under ultraviolet illumination. This study illustrates how compositionally stepped FGMs can combine electronic and optical functions in a single bulk part, opening pathways for cost-effective, multifunctional devices.

Functionally Graded Materials: Fabrication and Mechanical Properties publication trend

The graph below shows the total number of articles in functionally graded materials: fabrication and mechanical properties across all publications each year (not limited to Nature Index journals).

Technical terms

Functionally graded material (FGM): A composite whose local composition or microstructure changes systematically to produce spatial variation in properties.

Additive manufacturing (AM): A layer-by-layer fabrication technique enabling complex geometries and controlled material gradients by varying feedstock composition or process parameters.

Power-law gradient: A mathematical model describing the continuous variation of constituent volume fractions or properties according to a power-law function across a material’s thickness.

Spark plasma sintering (SPS): A rapid consolidation method using pulsed electric current and uniaxial pressure to join powder layers or mixed powders into dense graded structures.

Photoluminescence: The emission of light from a material following optical excitation, used to characterise the optical performance of doped graded composites.

References

1. Functionally graded materials (FGMs): A review of classifications, fabrication methods and their applications. Processing and Application of Ceramics (2021).
2. Functionally Graded Materials: An Overview of Stability, Buckling, and Free Vibration Analysis. Advances in Materials Science and Engineering (2019).
3. Vat Photopolymerization Additive Manufacturing of Functionally Graded Materials: A Review. Journal of Manufacturing and Materials Processing (2022).
4. Fabrication of a Functionally Graded Copper-Zinc Sulfide Phosphor. Scientific Reports (2016).
5. Functionally Gradient Material Fabrication Based on Cr, Ti, Fe, Ni, Co, Cu Metal Layers via Spark Plasma Sintering. Coatings (2023).
6. Elastic Buckling Behavior of Functionally Graded Material Thin Skew Plates with Circular Openings. Buildings (2024).