Quality Control Evaluation of Additive Manufacturing Powders Using Light and Electron Microscopy

Predictable and successful use of metallic powders in additive manufacturing applications requires consistency in both the physical and chemical characteristics of the powder feedstocks. Metallographic methods using light and electron microscopy have been developed to provide data relevant to these characteristics. Physical properties, such as particle size and shape distributions, affect the part build, while the nonmetallic inclusion content and particle-to-particle chemical uniformity influence part properties. Light optical techniques are used to estimate the particle size and shape distributions, in addition to estimating the nonmetallic inclusion content of the powder volume, while electron microscopy is utilized to determine the particle-to-particle chemical uniformity, with the aim of determining the presence of chemically dissimilar particles. The methods used for sample preparation, along with details of the test methods and representative test data will be discussed.