Ion Channeling Imaging for Rapid Grain Boundary Mapping
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Solution Overview
Problem
Current techniques for high-resolution material characterization, such as EBSD and EDS, are time-consuming and impractical for rapid surface mapping due to the need for numerous dwell points and long dwell times, resulting in low-resolution images when attempting to speed up the process by spacing dwell points further apart or reducing dwell time.
Innovation Solution
The use of ion channeling imaging to rapidly delineate grain boundaries, allowing for shorter dwell times and closer spacing of dwell points, followed by analysis with EBSD or EDS at fewer points within each grain, and the application of spin indexing to determine crystal structure and orientation with multiple ion channeling images at different angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If EDS or EBSD techniques are used to map a surface with high resolution, then accurate material characterization is achieved, but the mapping process becomes extremely time-consuming
Solution Approach 1:
The patent segments the mapping process into two distinct phases: (1) rapid ion channeling imaging to delineate grain boundaries and define regions of interest, and (2) subsequent EDS/EBSD analysis only within those defined regions. This segmentation allows the time-consuming high-precision techniques to be applied only where necessary, rather than across the entire surface, thereby resolving the contradiction between measurement precision and time consumption.
Solution Approach 2:
The patent applies preliminary action by using ion channeling imaging first to pre-define grain boundaries and identify regions of interest before performing EDS or EBSD analysis. This preliminary step creates a roadmap that guides subsequent analysis, ensuring that high-precision measurements are concentrated in the most relevant areas, thus reducing overall mapping time while maintaining characterization accuracy.
2Measurement precision
If the number of dwell points is increased to improve image resolution, then higher resolution images are obtained, but the total analysis time increases significantly
Solution Approach 1:
The patent applies local quality by concentrating high-resolution EDS/EBSD measurements only within grain interiors that have been identified by ion channeling imaging, rather than uniformly sampling the entire surface. The ion channeling image provides grain boundary definition, and subsequent analysis is localized to specific grain regions, allowing high resolution where needed while minimizing unnecessary measurements in boundary areas, thus resolving the resolution-time contradiction.
3Productivity
If dwell time is reduced to speed up mapping, then mapping time decreases, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent segments the measurement process so that ion channeling imaging (which is rapid) defines grain boundaries, and then EDS/EBSD measurements are performed with adequate dwell times only within those defined grain regions. This segmentation allows the system to maintain high productivity through rapid boundary definition while ensuring sufficient signal-to-noise ratio in the subsequent focused analysis, resolving the contradiction between mapping speed and measurement precision.
4Loss of information
If slice-and-view technique is used to obtain three-dimensional images by removing material, then volumetric information is obtained, but the surface area increases requiring prohibitively long mapping times
Solution Approach 1:
The patent applies segmentation by using ion channeling imaging to rapidly define grain boundaries and regions of interest on each exposed surface after material removal, before performing time-consuming EDS/EBSD analysis. This allows the slice-and-view technique to proceed efficiently through multiple slices, with each slice's grain structure quickly identified and then analyzed only in relevant regions, making three-dimensional mapping feasible despite the increasing surface area across multiple slices.
Solution Approach 2:
The patent applies preliminary action by performing ion channeling imaging on each slice to pre-define grain boundaries and identify regions of interest before conducting detailed EDS/EBSD analysis. This preliminary step on each exposed surface ensures that subsequent high-precision measurements are focused only where necessary, making the multi-slice three-dimensional reconstruction process time-efficient despite the cumulative surface area across all slices.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables rapid and high-resolution mapping of crystal grain properties, reducing the number of required dwell points and improving image resolution while minimizing sample damage, and allowing for efficient three-dimensional representation of the work piece.
Implementation Method 1
scanning an ion beam across an exposed surface of a work piece to determine grain boundaries. An ion channeling image of the work piece is obtained to determine boundaries of individual grains
Implementation Method 2
the ion beam causing the emission of secondary electrons at multiple imaging points of the scan
Implementation Method 3
an electron beam is directed toward a sample and excites inner shell electrons of the sample. The decay from the excited state back to a lower energy state yields an x-ray with a energy/wavelength characteristic of the atom from which it was emitted
Implementation Method 4
Electrons that are backscattered near the surface are diffracted after scattering off crystal planes in the sample
Data Source
AI summary
A system and method of characterizing a work piece, comprising:scanning an ion beam across an exposed surface of a work piece, the ion beam causing the emission of secondary electrons at multiple imaging points of the scan, the number of secondary electrons emitted varying at different ones of the multiple imaging points;detecting the emitted secondary electrons at each of the multiple imaging point to form an image, the brightness of each point in the image being determined by the number of secondary electrons detected at a corresponding imaging point on the work piece;determining grain boundaries in the work piece using the differences in brightness at different points in the image, the grain boundaries defining multiple grains;directing a charged particle beam toward one or more analysis points within one or more of the grains, the number of the one or more analysis points within each grain being less than the number of imaging points within the same grain; anddetecting emissions from the work piece sample at each analysis point;and determining the composition or crystal structure of one or more grains based on the detected secondary emissions.