EBSD in China

Sophie Yan, Applications Engineer, EDAX

EBSD in China is a big topic and it may sound as though I am not qualified to judge or to summarize the current situation. However, as I have worked with EBSD applications for several years, I have personal experience to share. More than ten years ago, I didn’t know about EBSD when I was studying the microstructure of materials. I was in Shanghai at that time and the environment was kind of open. It is probably that at that time in China: very few people knew about EBSD. Today the situation has changed enormously after just after 10+ years. Most researchers now try to put EBSD on their microscope. Microscopes including EDS and EBSD capability are standard in Chinese universities.

As an Applications Engineer, I visit research organizations, companies, and factories. I meet customers from many different backgrounds. Some of them are experts but more are new to microanalysis, especially students from science and engineering universities. They may each have a different focus, but they all have high expectations of EBSD. The professors care about the functions which can solve their issues. If there is currently no such function, then they often ask if we can add it. Entry level users prefer to learn how to operate the microscope and detectors quickly so that they get their results as soon as possible. The most frequent question asked is, what can EBSD do? Then I begin my introduction and I see that they become more and more interested. Sometimes they have high expectations. For example, when I demonstrate stress/strain analysis, I am often asked how to get stress value. This is a common misunderstanding because as an indirect way technique, EBSD can show the strain trend of materials, but it is beyond it to measure stress value.

My routine work includes introduction and training. Over a period of time, I can see a newcomer becoming more experienced and getting his own results, which makes me proud as a supporter. Whereas I care about the EBSD technology itself, the customers are more interested in learning how to use it in their work to solve some of their analysis challenges. They often give me new ideas and make me aware of other areas besides pure technology, for example, how to remove the users’ initial fear for EBSD. As a student majoring in material science I thought crystallography was very different from the reality I now understand. As a ‘teacher’ I am not focused on how to keep our users’ interest on EBSD and reminding to them to use it regularly. Fortunately, social media has improved the speed and consistency of our communication. When issues are solved quickly, people think the EBSD technique is less difficult. Effective communication contributes to the technology transfer.

The level of adoption of EBSD hardware in China is excellent, but the usage of and research into the technique is still in its infancy. I have spoken to many people about this issue. The interesting thing is that outsiders tend to give an optimistic perspective. An Australia professor told me several years ago that we should be taking a longer-term view and that there would probably be, a tremendous change in the next ten years. Quantitative results make a qualitative change. I hope he is right!

Fortunately, EBSD usage in China has increased greatly and continues to increase, which shows us a promising future.




Avoid a Distorted View

Dr. Stuart Wright, Senior Scientist EBSD, EDAX

In the world of “fake news” and “alternative facts”, it is important that we dig a little deeper than the headlines to understand the world around us and to avoid a distorted view those in power often want to give us. Ironically, the same is true at the microscale. I recently ran into some work concerning the effects of sample prep on x-ray measurements. It made me reflect on some early work we did to explore the effects of sample prep on EBSD results.

In order to prepare EBSD samples properly it is important to understand that surface finish is not the whole story. It is important that the layer of material sampled by EBSD be distortion free. Charts shown in many metals preparation handbooks clearly show that there can be significant deformation imparted into the sub-surface of a material during preparation. Consider the following chart adapted from a figure in a classic EBSD sample preparation paper: D. Katrakova & F. Mücklich (2001) “Specimen preparation for electron Backscatter Diffraction. Part I: Metals” Praktische Metallographie. 8:547-65. This plot clearly shows why sample prep for EBSD needs to be meticulous.

My longtime colleague, Matt Nowell, did a nice study comparing by grinding two samples, one ground to 240 grit and one to 1200 grit. He then cross-sectioned these samples and carefully prepared the cross-sectioned surfaces. Matt then did OIM scans on the two surfaces. Using a Kernel Average Misorientation (KAM) map, the degree of deformation in the 240 grit sample is clearly more pronounced that in the 1200 grit sample. Matt and I have always wanted to repeat this measurement for more grits and materials but have never found the time to pursue it again.

Many times, students who have asked me “which grinding and/or polishing steps can I skip?” Or, “how many times can I really use a grinding paper?” (I remember as a student we got one paper for each grit for the semester and we would hang them from a wire with clothes pins in the sample prep lab!). Or, “can’t I just do the final grinding step for a longer time and skip the coarser grinding steps?” One thing we’ve learned on our own and in conversations with the sample prep vendors is that the recipes developed with several steps for what intuitively may feel like short times really are the steps that lead to the best results -basically confirming the plot shown above.

The improvement in cameras, image processing and particularly NPAR™ should not be used as an excuse to take shortcuts in sample prep. While it may be possible to get patterns and reasonable maps, are you really looking at the representative microstructure of interest or a distorted version resulting from deformation induced by sample prep?

I believe EBSD has had a positive impact on the metallography community. EBSD has forced us to be more careful in sample preparation over that typically done for light microscopy or even scanning electron microscopy. Hopefully that extra care has resulted in more representative microstructural characterization.

Seeing the World a Little Differently.

Jonathan McMenamin, Marketing Communications Specialist, EDAX

When I started at EDAX five years ago, I knew very little about materials analysis. My education was in Management Information Systems and Computer Science and my work experience came from spending eight years in the Sports Information department at Rowan University. Little by little, I have learned more about the various analysis techniques and feel comfortable enough to write this blog.

One of the first things that caught my eye at EDAX was a series of maps generated from Energy Dispersive Spectroscopy (EDS) and Electron Backscatter Diffraction (EBSD) analysis. The vibrant colors and patterns are very beautiful and almost look like art. Lately, I have noticed objects in everyday life that remind me of these maps.

This past July, my wife and I and our friend took a trip to Ireland. We visited Slieve League in county Donegal, one of the highest sea cliffs in Europe (1,998 feet from the highest point). We decided to hike up the cliffs for a bit and on our way up the rocky pathway on this rainy, foggy day, I came across a large rock that grabbed my attention. It was covered in a pattern that reminded me of an EBSD map showing grain boundaries. I quickly snapped a few photos (below) to show to our EBSD product manager, Matt Nowell when I returned.

Photos of a rock taken at Slieve League in Donegal, Ireland.

A few weeks later, I was at a restaurant in the St. Louis Lambert International Airport having dinner with a few of my coworkers following a successful Microscopy & Microanalysis (M&M) show. While we were waiting for the waitress to return with our food, I looked up at the light hanging over the table next to ours and noticed that it resembled an EBSD pattern. I found another example of a beautiful glass piece when I was decorating my Christmas tree with my wife a few weeks ago. My wife’s grandmother and aunt give her gorgeous hand-blown glass ornaments from Cape Cod every year. As I was hanging one on the tree, I took a photo and explained to her that it looked like the maps we produce at work.

Light in a restaurant at the St. Louis Lambert International airport. One of my family’s hand-blown glass Christmas ornaments.

Ever since I was little, I have had a fascination with the ocean and sharks in particular. One of my favorite species is the Rincodon typus, more commonly known as a whale shark. It is not only the largest living nonmammalian vertebrate, but the whale shark has a very particular pattern of pale yellow spots and stripes on its skin. When I was putting together the EDAX Interactive Periodic Table of Elements (http://www.edax.com/resources/interactive-periodic-table), I came across a map of nickel nanopillars on indium at 3 kV demonstrating low kV microanalysis, and I immediately though it resembled a whale shark.

Rincodon typus, commonly known as a whale shark. Low kV microanalysis: nickel nanopillars on indium at 3 kV.

My final example comes from one of my favorite television shows, The Curse of Oak Island on the History Channel. The show follows a group of men that are in search of treasure that is supposedly buried on a small island off the coast of Nova Scotia, Canada. Several theories exist as to what the treasure is exactly, ranging from Knights Templar hiding sacred religious relics to pirates burying gold and jewels. The group has uncovered many clues and they have found various interesting items including ancient coins, bones from the 1600s, and pieces of wood, ceramic, and paper. On an episode in the current season (season 5), the group discovered a rose-headed spike while metal detecting near the coast line. If I had watched this prior to working at EDAX, I probably wouldn’t have thought anything about it. However, now that I know much more about microanalysis, I immediately thought to myself that they should use EDS analysis to find out what elements the metal was comprised of, to possibly date it based on what materials were used during that period for creating spikes. As it turns out, that is exactly what they did. The team found out that the spike was comprised of 90% iron and 10% carbon with no traces of manganese or sulfur. This showed that it was pre-1840s when manganese was used in metal work and that it was smelted with charcoal before the use of fossil fuels in the 1700s. All pointing to the fact that people were on Oak Island hundreds of years ago.

Rose-headed spike.

The world of microanalysis is extremely interesting and present all around us, you just have to keep your eyes open to see where it pops up in your daily life.

EBSD and the Real World

Shawn Wallace, Applications Specialist, EDAX

One of the powers of EBSD is showing how microstructures are created by the processing of a material and how these microstructures can change the material properties of a sample. Explaining this connection to novice users or potential customers can be difficult. Luckily for me, my sidewalk has given me a perfect example.

It is made up of oriented bricks. Some are placed square side up. Some are placed rectangular side up. But look at the color? Why are some bricks wet while others are dry? The square sides tend to be dry, rectangular still wet.

Now let’s start building up a case as to why this happens.

The first step is understanding how these bricks are made and what they are made of. You take clay, you slap it into a mold. You press the rectangular side to compress it to fill the mold. Fire it and tada, you have a brick. A lot is going on in these steps that you can’t see with the naked eye.

The main thing is that the squeezing step is really having a profound effect on the brick. You are taking randomly oriented platy minerals (Figure 1) and giving them a preferred orientation by squeezing them (Figure 2). It is like a house of cards that has fallen down. You now have grains lying down. Water can’t break through the new “sheets”, but turn the brick on its side and you have pathways to drain the water.

Figure 1. Clay minerals in bricks are often platy in shape. Without any outside forces, the grains are randomly orientated.

FIgure 2. By compressing the material to form a brick shape, the grains are laid flat relative to each other. This is much like EBSD samples with a texture.

This is what you are seeing here. The square bricks have clays that are oriented to wick the water deeper in to the brick, while on the rectangular faces, the water has nowhere to go (Figure 3). Square bricks wick away and are dry, while rectangular faces are still wet.

Figure 3. After the brick is pressed, there are no connecting paths for the water to flow into the material from the top. But from the side, there are channels leading into the bricks. This is what allows the water to wick inside the brick from the square side, but not the rectangular side.

On a high level, this is what EBSD is all about. You are seeing how these processes forming a material are now controlling how the material behaves. For EBSD, these can be electrical, thermal, or mechanical properties, but EBSD is the driving force to truly understanding how and why your material behaves the way it does.


Materials Selection While Black Friday Shopping

Matt Nowell, Product Manager EBSD, EDAX

I’m writing this blog the Monday after the Thanksgiving holiday, and having survived a Black Friday shopping adventure that started just a couple of hours after finishing the turkey last Thursday. While waiting in line for the doors to open and the tryptophan to wear off, I worked on plotting a strategy through the store to find a robotic vacuum cleaner, an Amazon Echo, some LED lights for outside, and the latest Minecraft toy for my youngest son. As the clock ticked towards 6 P.M., I felt confident in my plan and ready to go.

When the doors opened, and folks started streaming in, I grabbed a cart. This is always a tricky decision, as it immediately limits your mobility and possible escape routes. However, I knew ironically that the vacuum robot wasn’t going to push himself around quite yet. With cart in hand, I had to take a wider path, so I went a circuitous route to avoid the anticipated crowds, and ended up in housewares near where I expected the robot to be.

The first thing that caught my eye though wasn’t the vacuum cleaners, or the shiny Christmas plates, it was the cooking pans. It wasn’t the color, or size, or even price that piqued my interest, it was the material on the label: Titanium.

Now I’m no gourmet chef, but I generally don’t think of Titanium as a material used for pans. I’m more familiar with its applications in aerospace engine applications, in medical implants (see https://edaxblog.com/2014/01/22/bringing-oim-analysis-closer-to-home/), and in golf clubs. I’ve certainly polished more Titanium samples than I want to remember. Seeing these Titanium pans, it got me thinking about material selection, how material scientists must balance different materials properties (and cost) to match a material with an application, and where Titanium fits in the world of cooking.

One of my favorite cookbooks is “The Food Lab”, by J. Kenji Lopez-Alt, which has the sub-title “Better Home Cooking Through Science”. I’ve enjoyed reading this book because the author systematically tackles questions like “Is New York pizza better because of the water?” using the Scientific Method, and writes humorously about the results as well as providing delicious recipes. I’ve also taken to following him on Twitter (@TheFoodLab), and a recent post shows the pictures, (shown here as Figure 1), using an Infrared (IR) camera, of skillets made of different materials.

Figure 1. Heat distribution in pans made of different materials.

I found it a fascinating picture visualizing the heat distribution, derived from the thermal conductivity of the materials. Stainless steel is non-reactive, so you can cook anything in it. However, it doesn’t have the greatest thermal conductivity. Cast iron has a similar issue, and takes a while to warm up but once it’s hot, it stays hot, which is great for searing meat. Aluminum has better thermal conductivity, but also soft, scratchable, and can react with some foods. Copper is another material with excellent thermal conductivity, but it is reactive to certain foods. When confronted with these types of property challenges, material scientists like the best of both worlds, so composite pans have been made where copper and/or aluminum are sandwiched with steel to try and combine thermal performance with a non-reactive surface.

So what advantages does Titanium bring to this application? As with the aerospace and recreational applications, Titanium has a good strength to weight ratio. It’s lighter than steel and stronger than aluminum, as well as being corrosion-resistant. This means it’s the lightest cookware you can buy. Not necessarily the most important feature in the kitchen, but it does have value for cookware designed for camping.

All this thinking about optimization of thermal conductivity made me think about work done on thermoelectric materials. These materials convert a temperature differential into an electrical potential. Unlike these cooking pans, these materials want to minimize thermal conductivity while maximizing electrical conductivity. This is an interesting challenge. Thermoelectric properties can be optimized by increasing grain boundary density to disrupt phonon heat transfer. Figure 2 shows an EBSD IPF map of a Bismuth Telluride thermoelectric material that was made by shock-wave consolidation. This manufacturing process was investigated as a way to consolidate thermoelectric powders while retaining the nanostructure. More information can be found in our paper at: https://link.springer.com/article/10.1007/s11664-011-1878-4.

Figure 2. EBSD IPF map of a Bismuth Telluride thermoelectric material that was made by shock-wave consolidation

In the end, I decided not to buy a pan, but I did get the robot vacuum cleaner. I look forward to asking Alexa EBSD-related questions, just to see what happens. I also hope Santa brings me something that is microstructurally interesting, that perhaps I’ll use in my next blog.

Looking At A Grain!

Sia Afshari, Global Marketing Manager, EDAX

November seems to be the month when the industry tries to squeeze in as many events as possible before the winter arrives. I have had the opportunity to attend a few events and missed others, however, I want to share with you how much I enjoyed ICOTOM18*!

ICOTOM (International Conference on Texture of Materials) is an international conference held every three years and this year it took place in St. George, Utah, the gateway to Zion National Park.

This was the first time I have ever attended ICOTOM which is, for the most part, a highly technical conference, which deals with the material properties that can be detected and analyzed by Electron Backscatter Diffraction (EBSD) and other diffraction techniques. What stood out to me this year were the depth and degree of technical presentations made at this conference, especially from industry contributors. The presentations were up to date, data driven, and as scientifically sound as any I have ever seen in the past 25 years of attending more than my share of technical conferences.

The industrial adaptation of technology is not new since X-ray diffraction has been utilized for over half a century to evaluate texture properties of crystalline materials. At ICOTOM I was most impressed by the current ‘out of the laboratory’ role of microanalysis, and especially EBSD, for the evaluation of anisotropic materials for quality enhancement.

The embracing of the microanalysis as a tool for product enhancement means that we equipment producers need to develop new and improved systems and software for EBSD applications that will address these industrial requirements. It is essential that all technology providers recognize the evolving market requirements as they develop, so that they can stay relevant and supply current needs. If they can’t do this, then manufacturing entities will find their own solutions!

*In the interests of full disclosure, I should say that EDAX was a sponsor of ICOTOM18 and that my colleagues were part of the organizing committee.

Aimless Wanderin’ – Need a Map?

Dr. Stuart Wright, Senior Scientist, EDAX

In interacting with Rudy Wenk of the University of California Berkeley to get his take on the word “texture” as it pertains to preferred orientation reminds me of some other terminologies with orientation maps that Rudy helped me with several years ago.

Map reconstructed form EBSD data showing the crystal orientation parallel to the sample surface normal

Joe Michael of Sandia National Lab has commented to me a couple of times his objection to the term “IPF map”. As you may know, the term is commonly used to describe a color map reconstructed from OIM data where the color denotes the crystallographic axis aligned with the sample normal as shown below. Joe points out that the term “orientation map” or “crystal direction map” or something similar would be much more appropriate and he is absolutely right.

The reason behind the name “IPF map”, is that I hi-jacked some of my code for drawing inverse pole figures (IPFs) as a basis to start writing the code to create the color-coded maps. Thus, we started using the term internally (it was TSL at the time – prior to EDAX purchasing TSL) and then it leaked out publicly and the name stuck – my apologies to Joe. We later added the ability to color the microstructure based on the crystal direction aligned with any specified sample direction as shown below.

Orientation maps showing the crystal directions aligned with the normal, rolling and transverse directions at the surface of a rolled aluminum sheet.

The idea for this map was germinated from a paper I saw presented by David Dingley where a continuous color coding schemed was devised by assigning red, green and blue to the three axes of Rodrigues-Frank space: D. J. Dingley, A. Day, and A. Bewick (1991) “Application of Microtexture Determination using EBSD to Non Cubic Crystals”, Textures and Microstructures, 14-18, 91-96. In this case, the microstructure had been digitized and a single orientation measured for each grain using EBSD. Unfortunately, I only have gray scale images of these results.

SEM micrograph of nickel, grain orientations in Rodrigues-Frank space and orientation map based on color Rodrigues vector coloring scheme. Source: Link labeled “Full-Text PDF” at www.hindawi.com/archive/1991/631843/abs/

IPF map of recrystallized grains in grain oriented silicon steel from Y. Inokuti, C. Maeda and Y. Ito (1987) “Computer color mapping of configuration of goss grains after an intermediate annealing in grain oriented silicon steel.” Transactions of the Iron and Steel Institute of Japan 27, 139-144.
Source: Link labeled “Full Text PDF button’ at www.jstage.jst.go.jp/article/isijinternational1966/27/4/27_4_302/_article

We didn’t realize it at the time; but, an approach based on the crystallographic direction had already been done in Japan. In this work, the stereographic unit triangle (i.e. an inverse pole figure) was used in a continues color coding scheme were red is assigned to the <110> direction, blue to <111> and yellow to <100> and then points lying between these three corners of the stereographic triangle are combinations of these three colors. This color coding was used to shade grains in digitized maps of the microstructure according to their orientation. Y. Inokuti, C. Maeda and Y. Ito (1986) “Observation of Generation of Secondary Nuclei in a Grain Oriented Silicon Steel Sheet Illustrated by Computer Color Mapping”, Journal of the Japan Institute of Metals, 50, 874-8. The images published in this paper received awards in 1986 by the Japanese Institute of Metals and TMS.

AVA map and pole figure from a quartz sample from “Gries am Brenner” in the Austrian alps south of Innsbruck. The pole figure is for the c-axis. (B. Sander (1950) Einführung in die Gefügekunde der Geologischen Körper: Zweiter Teil Die Korngefüge. Springer-Vienna)
Source: In the last chapter (Back Matter) in the Table of Contents there is a link labeled “>> Download PDF” at link.springer.com/book/10.1007%2F978-3-7091-7759-4

I thought these were the first colored orientation maps constructed until Rudy later corrected me (not the first, nor certainly the last time). He sent me some examples of mappings of orientation onto a microstructure by “hatching” or coloring a pole figure and then using those patterns or colors to shade the microstructure as traced from micrographs. H.-R. Wenk (1965) “Gefügestudie an Quarzknauern und -lagen der Tessiner Kulmination”, Schweiz. Mineralogische und Petrographische Mitteilungen, 45, 467-515 and even earlier in B. Sander (1950) Einführung in die Gefügekunde Springer Verlag. 402-409 . Sanders entitled this type of mapping and analysis as AVA (Achsenvertilungsanalyse auf Deutsch or Axis Distribution Analysis in English).

Such maps were forerunners to the “IPF maps” of today (you could actually call them “PF maps”) to which we are so familiar with. It turns out our wanderin’s in A Search for Structure (Cyril Stanley Smith, 1991, MIT Press) have actually not been “aimless” at all but have helped us gain real insight into that etymologically challenged world of microstructure.