Steels and metal alloys

Duplex stainless steels possess a microstructure formed by two main phases: ferrite and austenite. They are used in a wide range of applications due to their advantageous properties.

High temperatures during the manufacturing processes can modify the balance of alloying elements and can lead to a drastic deterioration in toughness, corrosion resistance, and weldability of duplex stainless steels. Thus, detailed microstructure analysis of duplex steels is essential.

LiteScope benefits:

• The AFM-in-SEM approach enables fast and accurate localization of a single grain on the sample, and its thorough characterization including phase identification, crystallographic orientation, and topographical measurement.
• All in one measurement.

Published with courtesy: Marina Knyazeva, TU Dortmund, Germany

In this case, the AFM-in-SEM approach was further extended by adding a nanoindenter to the LiteScope scan head. Nanoindentation represents an extremely versatile technique to determine material mechanical properties at the nanoscale such as elastic modulus, hardness values, fracture toughness, or creep and yield stress. This hybrid technique enabled sample phase identification, precise indentation targeting, and topographical analysis – all in one measurement.

LiteScope benefits:

• Fast and precise identification of a wide range of separate phases of small size.
• Indentation of individual phases with nanometer precision.
• Precise indent analysis by AFM.

Published with courtesy: C. Julia-Schmutz, CSEM SA Neuchâtel, Switzerland

The fatigue crack propagation behavior of chromium steel was studied using the AFM-in-SEM technique in combination with a focused ion beam (FIB). The crack was initiated using the FIB on the steel sample mounted in a tensile/compression module and the propagation of the crack was simultaneously analyzed by both the AFM and SEM.  

LiteScope benefits:

• Precise initiation and location of the crack by SEM-FIB.
• Analysis of the crack propagation after cyclic loading by both techniques.
• 3D CPEM view enabled detailed analysis and a better understanding of the obtained data.

Published with courtesy: Ing. Ivo Kuběna, Ph.D.

Tungsten alloys represent promising candidates to replace tungsten in the first wall applications in future fusion facilities. Since tungsten is susceptible to oxidation at elevated temperatures, various oxide-forming elements (chromium, titanium, silicon) are being added to tungsten to induce self-passivation.

Herein, W-10Cr-1Hf alloy with hafnium oxide particle dispersion was prepared by spark plasma sintering, wherein unique features of the microstructure were discovered by the AFM-in-SEM approach.

LiteScope benefits:

• Fast and accurate localization of the region of interest. CPEM view. 
• Visualization of differences between material (SEM) and topography (AFM) contrast.
• CPEM can accommodate multiple channels (e.g. BSE,  SE, and topography).

Published with courtesy: Monika Vilemova, Institute of Plasma Physics AS CR, Czechia