The RTI R&D department has a Scanning Electron Microscope (SEM) equipped with EDAX Si(Li) detector and Phoenix software for Energy Dispersive Spectroscopy.

The SEM is a very useful investigative tool for materials and failure analysis as it can generate images of much higher magnification (up to 20,000X) compared to optical microscopy at a much greater depth of field. In addition, the contrast in an electron micrograph is representative of surface topography and composition as different elements and surface topography emit certain amounts of electrons characteristic of the element and surface.

The Energy Dispersive Spectroscopy (EDS) is an analytical technique used in concert with the SEM. EDS is used for the chemical characterization of a specimen used in concert with SEM for compositional microanalysis. It is useful for material characterization since it can perform qualitative and semi-quantitative microanalysis on a specimen from a relatively low (~25X) to high magnification (~20, 000X).

At RTI SEM-EDS technique is utilized to perform failure analysis, phase identification, micro chemical analysis and defect characterization

Benefits:

The SEM-EDS laboratory has been an integral part of RTI's commitment to customer support as it provides prompt response to customer inquiries by speedy resolution of material property issues.

The SEM-EDS technique enables:

• Identification of the chemistry and phases in an unknown material.
• Characterization of internal defects and impurities in a manufactured product to determine their distribution and morphology.
• Characterization of contaminants and corrosion products by microanalysis
• Determination of intra/inter phase elemental distribution through X-ray mapping.
• Determination of the mode of failure (corrosion, mechanical), fracture (ductile, brittle, fatigue overload), direction of fracture propagation and area and mechanism of fracture propagation through examination of fractomicrographs of a failed component at high magnifications.

In addition to providing customer support, SEM-EDS is also used for new alloy development, qualification of titanium alloys and characterization of metal/alloy surfaces to evaluate surface finish etc., for new business applications.

Relevant Projects:

• The SEM-EDS technique identified the source and root cause for extensive weld metal porosity in titanium alloy butt welded pipes stemming from titanium alloy filler wire surfaces.
• The SEM was a vital tool to determine the mode and root cause of repeated failure of a beta titanium alloy spring utilized in aircraft flight control system, to preclude future failures.
• The SEM-EDS technique is used to help in product quality improvement by characterizing and analyzing melt and mill product related defects permitting determination of origin and root cause to mitigate future occurrence.
• The SEM was used to define stress corrosion susceptibility limits in elevated temperature brine solutions by determining the onset of low energy fracture for a developmental titanium alloy designed for use in energy industry.
• The SEM is used in assisting customers to solve problems related to downstream processing of materials such as forming and fabrication.