SEM-EDS

SEM-EDS is the step taken when optical microscopy has reached its limit. It resolves features far below what light can show and identifies the elements present at a chosen point, so a fracture surface can be read for its mode of failure and a deposit, inclusion, or corrosion product can be identified rather than merely described.

What SEM-EDS does

Scanning Electron Microscopy (SEM) scans a focused electron beam across a specimen to build an image from the signals it generates. Compared with light microscopy, it delivers far greater magnification and a much larger depth of field, so rough, three-dimensional surfaces stay in sharp focus across their entire relief. Paired with Energy-Dispersive X-ray Spectroscopy (EDS), the same instrument also measures the elements present at a chosen location, turning a picture of a feature into a picture and a chemistry of that feature.

Imaging that light can't reach

Because SEM keeps deep, irregular topography in focus, it excels at the surfaces that matter most in a metallurgical investigation:

• Fracture surfaces (fractography): resolving the fine features that reveal how a part broke
• Corrosion products: pits, scales, and attack morphology at the micron scale
• Deposits and scale: layered build-up on tubes, valves, and process surfaces
• Inclusions and second phases: non-metallic particles within the metal matrix

Fracture mode identification

Fractography under the SEM lets us distinguish the mechanisms behind a failure by their characteristic surface signatures: fatigue striations, dimpled rupture from ductile overload, and intergranular cracking that follows grain boundaries. Reading these features is central to determining not just that a component failed, but why.

Elemental micro-analysis with EDS

EDS collects the characteristic X-rays emitted under the electron beam to identify which elements are present. It can be run in several modes to match the question:

• Spot analysis: chemistry of a single feature such as an inclusion, particle, or crack origin
• Area analysis: an averaged composition across a defined region
• Elemental mapping: spatial maps showing how elements are distributed across a field of view

Typical applications

SEM-EDS supports a wide range of investigations, including failure analysis and fracture mode identification, corrosion and deposit identification, weld and inclusion analysis, and contamination identification. When a component underperforms, corrodes, or fails, the combination of high-resolution imaging and on-the-spot elemental chemistry provides the evidence needed to reach a defensible conclusion.