Routine Low kV EBSD at Very High Speed

Electron BackScatter Diffraction (EBSD) has become a ubiquitous SEM-based technique for quantifying the microstructure and crystallographic texture of bulk samples. Acquisition speed and sensitivity are the main parameters defining the performance of any EBSD system. These two parameters are critical not only for maximizing productivity but also for enhancing data quality and integrity, e.g. increased hit rate and, respectively, reduced impact of beam instability.

Direct Electron Detection (DED) based EBSD detectors are significantly more signal-efficient than scintillator-based detectors. Yet, they have, so far, underperformed in terms of speed.

Bruker’s eWARP detector is a pioneering EBSD detector that combines Direct Electron Detection and CMOS technologies to push the limits of detector sensitivity and EBSD analysis speed. eWARP is capable of acquiring EBSD maps at speeds of up to 14,400 frames/second while requiring moderate beam currents and accelerating voltage.

In this example, an EBSD map was acquired in only 18 seconds from a duplex stainless steel using 10kV accelerating voltage and 12 nA beam current. More than 14,400 patterns were acquired and indexed every second. Without applying any data cleaning, the hit rate of this analysis was 98.5%. The analyzed area contains 1,525 grains with a mean equivalent diameter of 33µm. The grains were detected according to ASTM E2627. The duplex steel sample consists of an equal proportion of Ferrite and Austenite, with the Ferrite grains exhibiting signs of plastic deformation while most Austenite grains being fully recrystallized.