Modern materials — particularly those that have been additively manufactured to meet the rigorous quality demands of industrial applications — are increasingly complex. From lightweight alloys to intricate composite structures, understanding the behaviour and properties of these materials is critical. Yet, it can be difficult to gain a full understanding when relying on a single analytical technique. Here, Franz Kamutzki, Senior Account Manager at Thermo Fisher Scientific, explains how engineers and researchers can combine electron microscopy (EM) and micro-computed tomography (microCT) to obtain a deeper insight into materials at different length scales using a Hybrid Analysis Approach.
The Complexity of Modern Materials and Functionally Graded Materials (FGMs)
One example of the complexity of modern materials is functionally gradient materials (FGMs), which feature a continuously variable directional composition and structure to enhance performance characteristics. FGMs are particularly valuable in industrial applications where materials must withstand extreme thermal, mechanical, or chemical stresses. For instance, aerospace components and high-performance coatings benefit from the ability to tailor material properties across a single part, improving durability and reducing failure risks. However, fully characterising FGMs is challenging, as their continuous compositional changes require a multi-scale analytical approach to ensure no critical variations are overlooked.
Combining EM and MicroCT for a Complete Material Understanding
Each analytical technique provides unique and complementary insights. EM delivers nanometre-scale resolution, offering detailed information about a material’s surface structure, composition and microstructure. This makes it an invaluable tool for studying fine structural details that influence material performance.
MicroCT, meanwhile, excels at non-destructive 3D imaging of larger samples, revealing internal features such as porosity, cracks and density variations. While its resolution is lower than that of EM, it provides a crucial macroscopic perspective, allowing researchers to understand how internal structures and defects are distributed throughout a material.
Benefits of a Hybrid Analysis Approach for Material Characterisation
By integrating EM and microCT, engineers and researchers can achieve a multiscale understanding of materials that neither technique can deliver in isolation. Bridging the gap between macro- and nanoscale analyses allows for comprehensive visualisation. For example, MicroCT’s 3D imaging maps large-scale defects, while EM adds detailed insights into smaller features such as grain structures and elemental composition.
Combining data from both techniques also enables the identification of defect locations, sizes and types with high accuracy. The insights gained from this Hybrid Analysis Approach can help engineers to refine manufacturing processes, thus improving material properties and performance.
Example: Additively Manufactured Copper Nickel Alloys in Rocket Combustion Chambers
Take, for example, cold spray additively manufactured (CSAM) copper nickel (Ni-Cu) alloys used in rocket combustion chambers. Additively manufacturing these components provides a way of producing complex, lightweight structures at lower costs and with faster iterative development times. However, in the case of combustion chambers, the components must also be able to withstand extreme thermal and mechanical stresses. For FGMs such as CSAM Ni-Cu alloys, relying on one analysis technique risks missing critical details about material properties. Given the potential safety issues that low-quality rocket components could cause, it is a risk that no engineer can afford.
In Multi-scale Characterisation of Functionally Gradient Bimetallic Ni-Cu CSAM Alloys, Yorston et al. demonstrate how employing a hybrid approach can help to tackle this issue. MicroCT was employed to visualise porosity distribution in 3D, revealing trends such as increased pore density in nickel-rich regions. Meanwhile, EM provided nanoscale data on defect morphology and elemental distribution, uncovering smaller defect classes that microCT could not detect. These insights informed adjustments to the alloy composition and processing parameters, ultimately enhancing material reliability.
The Scope of the Hybrid Analysis Approach Across Industries
The benefits of combining EM and microCT extend far beyond this example. In other industries that make use of additively manufactured alloys such as aerospace, automotive and energy, a combined microscale analysis approach ensures a thorough understanding of material properties. In these cases, the Hybrid Analysis Approach can help to accelerate iterative development, reduce failure rates and open the door to innovations that might otherwise remain out of reach.
Overcoming Challenges in Adopting the Hybrid Analysis Approach
Despite its potential, the widespread adoption of combined EM and microCT analysis faces challenges. For instance, in industrial applications where operators are not necessarily experts in specific microscopy techniques, this approach may be perceived as overly complex. Others may question its scalability for routine industrial use that requires the analysis of thousands of samples.
However, advancements in supporting software are helping to address these concerns. One such solution is Thermo Scientific Avizo Software, which plays a pivotal role in overcoming the barriers to adopting a combined approach by streamlining data correlation and visualisation.
Regardless of the scale and data modality used, Avizo provides digital imaging-based workflows to facilitate materials characterisation and quality control from a single environment. The software offers advanced automation capabilities, making it easy to create repeatable, reliable workflows to conduct analysis at scale.
For engineers that are less confident with image processing, the inclusion of artificial intelligence enables them to save time on complex analysis while ensuring results consistency. In addition, Thermo Fisher’s dedicated support team, training sessions and how-to guides help to reduce the learning curve for non-expert operators.
By bridging the gap between these two methods, Avizo ensures that the combined power of microCT and EM is both practical and scalable, ultimately driving faster, more informed decision-making in materials analysis.
Conclusion: The Future of Materials Characterisation
As materials continue to grow in complexity, embracing a Hybrid Analysis Approach can help engineers and researchers to unlock deeper insights into material properties. Combining EM and microCT with the support of visualisation software delivers a complete picture of materials from the atomic scale to the macrostructure. This hybrid approach enables better defect detection, process optimisation and product performance, ensuring that materials can meet the demands of modern engineering.
