Everything Material in Material Science

On October 6, 2025, NSL’s Dr. Ross Cunningham presented at the ASTM International Conference on Advanced Manufacturing (ICAM) in Las Vegas. Dr. Cunningham joined more than 1,100 scientists, engineers and industry leaders from 35 countries who attended the flagship event for additive and advanced manufacturing. Below is a summary of Dr. Cunningham’s presentation.

The Next Challenge of Additive Manufacturing

In a little over a decade, Additive Manufacturing (AM) has transitioned from a niche prototyping tool to a viable production technology for components used in aerospace, defense, and medical applications. While improvements in design principles and process controls have enabled broader adoption, material-related challenges remain one of the most challenging barriers to significant advancement, particularly as engineers are increasingly looking to AM for mission-critical parts operating in extreme environments, like rocket and jet engines.

As AM technologies aggressively push towards maturity, it is clear that the approaches that enabled early progress will not be sufficient for the next tier of performance and reliability, where the demands and challenges related to materials are stronger than ever. To put it simply: what got us here won’t get us there.

The ‘Element’ in the Room: AM Material Chemistry

Significant progress has been made in controlling microstructure and defects in commonly used AM alloys such as AlSi10Mg, Ti-6Al-4V, and CoCr. However, trace-level material chemistry and contamination have historically received less attention, despite their profound impact on material performance.

A notable exception is Ti-6Al-4V, where oxygen content plays a critical role in material qualification and differentiates Grade 23 from Grade 5 (≤0.13 vs 0.2 wt%). Oxygen levels strongly influence mechanical properties, making this parameter tightly controlled in aerospace and medical applications.

For many other alloys, even small concentrations (<1000 ppm) of certain elements can significantly alter performance. For example:

• As little as 200 ppm of iron in GrCop-42 can significantly reduce thermal conductivity
• Nickel-based superalloys can experience degradation in high-temperature mechanical properties due to just 50 ppm of oxygen or nitrogen

These sensitivities were historically managed through specially designed, tightly controlled processes such as vacuum investment casting, but AM introduces new exposure pathways that increase contamination risk.

Powder Feedstock: Balancing Flexibility and Risk

The use of powder feedstock for many metal AM provides a lot of flexibility to those processes, but adds complexity to material control. Fine powders possess high surface area, making them more susceptible to gas absorption — particularly oxygen and nitrogen — than cast or wrought forms. Economic and sustainability drivers further encourage powder re-use, amplifying the potential for contamination from poor handling or cleaning practices, as well as gradual chemical drift over time.

While powders are frequently used in traditional manufacturing processes for critical and highly regulated components, such as powder metallurgy alloys used in rotating hot-section jet engine components, the risks are real. A high-profile case in 2023 saw an engine manufacturer incur a $3 billion charge related to undetected powder contamination.

The opportunity for AM in critical applications is significant, but so are the material challenges associated with powder-based processes — reinforcing the importance of robust feedstock quality control and testing.

ICP-OES and ICP-MS: Essential Tools for Elemental Analysis

Two of the most widely used techniques for detecting elemental composition in AM powder feedstock are:

• ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy)
• ICP-MS (Inductively Coupled Plasma Mass Spectrometry)

These methods are particularly well-suited for powder materials, which are incompatible with other elemental analysis techniques such as spark-OES.

Sample Preparation Considerations

Both techniques require dissolution of a measured sample mass into an aqueous solution, typically using heated acids. Proper digestion is essential and demands experienced chemists, especially for corrosion-resistant or complex alloys. Incomplete or improper preparation can lead to significant errors due to precipitation or volatilization of elements.

Analysis Process

After preparation, the sample is introduced into a high-temperature plasma, where the sample is vaporized and constituent atoms ionized. The two methods differ in how they detect and quantify those ions:

• ICP-OES
  • Measures characteristic light emissions as excited ions return to ground state
  • Best suited for major and minor constituents
  • Typical detection range: ~100% down to ~0.1% (1000 ppm)
• ICP-MS
  • Directly measures ions based on mass-to-charge ratio
  • Ideal for trace and ultra-trace elements
  • Typical detection range: ~0.5% (5000 ppm) down to ~0.001% (10 ppm) or lower

When used together, ICP-OES and ICP-MS provide a comprehensive chemical profile across approximately 70 elements, spanning bulk to trace levels, offering robust insight into powder chemistry. Further, unlike other methods such as Spark-OES or XRF, they don’t require certified reference materials.

Key Considerations for Accurate Trace Element Testing

While powerful, ICP methods are not without limitations. Critical factors influencing accuracy include:

• Proper sample digestion procedures
• Spectral and matrix interferences
• “Bulk” analysis methods can miss small-scale contamination
• Inability to detect every element

Understanding these limitations — and working with an experienced testing laboratory — is essential for generating reliable, actionable data.

LECO Analysis: Quantifying Critical Non-Metallic Elements

LECO analysis provides essential insight into non-metallic and interstitial elements that are impossible or impractical to measure through ICP techniques, such as oxygen, nitrogen, carbon, and sulfur. There are a few techniques that fall under the category of LECO testing:

• Combustion Analysis (NDIR Detection)
  • Carbon: ~50 ppm to 20%
  • Sulfur: ~10 ppm to ~10%
• Inert Gas Fusion
  • Oxygen and Nitrogen: ~10 ppm to ~40%
• Thermal Conductivity / NDIR Detection
  • Hydrogen: ~1 ppm to ~0.1%

Together, these methods enable highly sensitive measurement of elements that play a critical role in many material properties, often at low concentrations. As with ICP, these are robust methods that can characterize a wide variety of materials with wide detection windows for their target analyte. However, certain materials — such as aluminum, magnesium, and precious metals — can present added complexity.

Key Considerations for LECO Testing

• Method limitations and element-specific constraints
• Highly reactive metals (e.g., Mg, Al) may be incompatible with certain equipment
• Powder contamination via absorption may require periodic LECO testing beyond initial lot acceptance

SEM & EDS: Evaluating Physical Characteristics and Foreign Body Contamination

Scanning Electron Microscopy (SEM) is a powerful tool for assessing the physical characteristics of AM feedstock, including particle morphology, size distribution, and contamination.

When paired with Energy Dispersive Spectroscopy (EDS), SEM can also perform localized, semi-quantitative elemental analysis of individual particles. This capability is particularly valuable for identifying surface contamination and foreign-body contamination. This is one of the main uses for powder, as small amounts of foreign-body contamination (such as refractory particles from the powder manufacturing process) cannot generally be detected through bulk analysis like ICP or LECO.

However, SEM/EDS has some limitations as a quality control tool and is not a replacement for quantitative trace-level elemental analysis. Challenges include ensuring representative sampling, differentiating signal from noise at low concentrations, and the inherent limitations of detecting light elements. Additionally, elemental mapping and contamination analysis are often labor-intensive and time-consuming processes.

Key Considerations for SEM Analysis

• Often time-intensive manual evaluation (unless automated)
• Risk of non-representative sampling
• EDS is at best ‘semi-quantitative’ without a flat polished surface
• Limited sensitivity for trace and light elements

Measuring Moisture Content in AM Feedstock

Moisture plays a critical role in powder behavior and final part quality. Water readily adsorbs to the oxide layer of metal powders, contributing to oxidation, gas porosity, reduced flowability, and downstream performance issues.

Karl Fischer (KF) Titration is the industry gold standard for moisture measurement in AM feedstock, using the oven desorption technique. This approach enables accurate quantification of moisture across a broad range, typically as low as ~10 ppm.

For an in-depth look at Karl Fischer Titration, see our webinar on Karl Fischer analysis for AM Powder.

Key Considerations for Moisture Testing

• Karl Fischer measures moisture only, not other surface absorbed species
• Proper control of sample required as powder can easily pick up moisture from its environment

Looking to the Future: Dynamic Property Analysis for AM Powders

Another challenge of using powder feedstocks in AM is that while all of the above-mentioned chemical and material requirements are critical to the properties of the end-part, getting the feedstock to behave in a predictable manner is equally critical to the success of the manufacturing process. Tests for essential powder characteristics like packing density and flow have been around for decades, but new metrics like spreadability are unique to AM. New tools and methods are being developed to characterize these properties and give insights into how the multitude of measurable powder properties affect behavior in the AM process.

One such method is dynamic avalanche rheometry. This method uses a rotating drum powder rheometer that evaluates dynamic flow by recording how the powder tumbles, shears and cascades under rotation and vibration. This test provides key information on the powder’s flowability in a measurable form, giving more insight into how they will behave in the AM process compared to traditional characterization techniques.

Advancing AM Through Better Feedstock Control

As additive manufacturing continues its evolution into higher criticality applications, material considerations like controlling chemistry at the trace level are no longer optional — they are fundamental. Fortunately, many of the tools and techniques to address these challenges are well-established, and new ones are rapidly advancing.

By pairing awareness of contamination risks with robust analytical methods such as ICP-OES and ICP-MS, manufacturers can significantly improve confidence in their feedstock, enhance process consistency, and ensure the performance of AM components in the most demanding environments.

Looking to dive deeper into how third-party testing can support your unique material needs? Check out NSL’s resources below:

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