Materials Engineering, Inc.
47W605 I.C. Trail
Virgil, IL 60151
Of Materials Interest1998 Spring
Backscattered Electron Imaging
Do You Know Everything We Do?
MEi President on Careers CD
MEi Briefs
The Lighter Side
Ann Landers: On Product Safety!
The "What Is It?" Contest

Backscattered Electron Imaging:
What It Is and What It Can Do For You
While most of us have been exposed to or are familiar with the scanning electron microscope (SEM) as a powerful tool for failure analysis and contamination identification, you may not be familiar with the use of the SEM in the back-scatter image analysis mode, commonly referred to as BEi or simply back-scatter.
What is it?
In normal mode, the SEM creates an image by gathering the low energy secondary electrons which are ejected from the atoms within the sample. In the back-scatter mode, high energy electrons from the incident beam "bounce" off the atoms of the sample and are gathered. The intensity of the image is related to how many electrons bounce off or are scattered back, hence the term back-scattered. The heavier elements, such as tungsten and molybdenum, have larger nuclei and thus have a higher probability of creating back-scattered electrons. The energy of back-scattered electrons does not vary with the element, only with the operating voltage of the SEM.
In the conventional SEM photo (left) the metal shaving all look alike. However, the contrast difference in the backscatter image (right) reveals the shavings are a misture of three different metals.

45X 45X

What does this really mean?
The information provided by each mode is dramatically different. In the normal secondary electron mode, the contrast observed is due primarily to topography, and is generally rather low. In the back-scatter mode, the contrast observed is due to differences in atomic number. The high atomic number elements (e.g. molybdenum, tungsten and lead) appear bright in contrast to the low atomic number elements (e.g. aluminum, silicon and titanium).
Uses of BEi
Back-scatter allows for quick and easy identification of phases with different elemental compositions. What does this mean in a practical sense? In a tool steel, the tungsten and molybdenum carbides appear brighter than chromium carbides, permitting quick differentiation. In leaded bronze, a segregation of the lead phase within the structure stands out against a dark background. Heavy metal platings appear white on a fracture surface, providing insight into whether a crack occurred in manufacturing prior to plating, or during usage.
The photographs show a group of metal shavings. In the conventional SEM photograph, all the shavings appear the same shade of gray. However, in back-scatter imaging, the shavings appear as bright, gray, and dark. EDS analysis confirms the shavings to be a mixture of aluminum (dark), steel (gray) and silver plating (bright).
Back-scattered electron imaging is a good complement to conventional secondary electron imaging on the scanning electron microscope, and is a powerful tool for certain applications. If you have a materials processing problem that you think back-scatter imaging would be the ideal tool to help you resolve, just give us a call to discuss the possibilities.

Do You Know Everything We Do?
While many of our customers have worked with us on several projects through the years, we are sure that some of our customers may not be familiar with the full range of services we offer. Hopefully, this list will give you a better idea of the range of services we offer. As always, we have an open invitation for any of our customers to come to Virgil to see how we do things.
Our Services
Failure Analysis
• Wear
• Fatigue
• Corrosion
• Hydrogen Embrittlement
• Ductile or Brittle Overload
• Improper Design or Misuse
• Material & Processing Defects

Contamination Identification
• Residues and Surface Films
• Corrosion Products
• Wear Debris
• Particles
• Plating & Joining Adhesion Problems
• Electronics, Medical Contaminants

Complete Metallurgical Laboratory
• Scanning Electron Microscopy
• EDS Chemical Analysis
• Metallography and Microscopy
• Microhardness and Hardness

Analysis of Processing Problems
• Welding, Brazing and Soldering
• Stamping and Metal Forming
• Casting and Forging
• Plating and Coating
• Heat Treating
• Powder Metal

Engineering Services
• Design Support
• Materials Selection
• Problem Analysis & Corrective Action
• Materials and Process R&D

We Also Provide
• On Site Investigations
• Specialized Product Testing
• Expertise in Electronics, Ceramics & Polymers
• Product Liability Investigations
• Expert Testimony

And Tensile strength, chemical composition, FTIR, physical properties and
corrosion testing are available though our network of associated laboratories.

MEi President on Careers CD
Last spring, video production specialist Elizabeth Hogan of Ruder-Finn in New York City spent a day at the MEi facility in Virgil, Illinois interviewing Bill Durako about Careers in Metallurgy and Materials Engineering. The interview is part of a project called the Career Resource Center (CRC) being developed by TMS-AIME for the materials engineering profession.
The CRC project is funded by the Arthur P. Sloan Foundation. It features interviews and comments with professionals in a variety of technical professions, including materials, mechanical, electrical, chemical and civil engineering, as well as physics, chemistry, geology and mathematics.
The project is targeted primarily at high school students. The goal of the project is 'to build public awareness of Science and Engineering fields and to provide students with comprehensive information with which to make informed academic and career decisions.'
TMS of AIME was selected to develop the Materials Science and Engineering portions of the CRC, and hopes to use the project to demonstrate the many opportunities available to students studying materials engineering.
The completed project will consist of an interactive CD ROM to be distributed to high schools and universities, a World Wide Web site that will offer a wealth of academic and statistical information, and an accompanying booklet for student distribution listing key facts on accredited university science and engineering programs, and course requirements. The high tech interactive presentation is full of examples aimed at being entertaining as well as informative. The multimedia format will feature Quicktime video clips with practicing engineers. Bill Durako is one of these so called 'Featured Engineers'.
The interview covered everything from a typical day and the most enjoyable aspects of the job, to how he decided to pursue the career path and what advice he would give to others interested in this field. Both the CD-ROM and World Wide Web site feature "Live from the Home Offices in Virgil, IL: Bill's Top Ten List of Things to Assist You in Your Engineering Career."
The CD-ROM is in the final stages of production and is scheduled to be released this summer. The world wide web site has many of the features completed, but is still under construction. You can check on the progress at www.crc4mse.org.
"I enjoyed being a part of this project. I know many high school students struggle with what they want to do with their lives. It's tough to make a decision without information. So many people either have a misunderstanding of what engineers do, or are pushed into engineering because they are good at math and science. Hopefully, the CRC CD-ROM and web site will provide insight into what engineers and scientists actually do, and help students with their career decisions."

MEi Briefs
Our customers will notice a self addressed stamped feedback card enclosed in many of our reports, especially to newer customers. The card contains 9 simple questions for you to evaluate our performance. We want to know what you think of your experience working with us. We are not the biggest in our field, but we are striving to be the best. Our goal is complete customer satisfaction, and the feedback cards are one way to help us get there.
One of the questions asks if you would like to meet with MEi engineers to discuss other materials and processing issues. We know that nothing can replace the meeting across the table to better understand your needs and our capabilities. We have many customers whom we meet with routinely as part of our projects with them, and we know that this has been a very effective tool. However, we know that this is not always possible, especially for many of our customers from coast to coast. Our goal this year is to visit more of you, our customers at your facility. And as always, you are always welcome to come to Virgil.

The Lighter Side
In case you've ever wondered why ignorance rises to the executive level, here is a simple explanation that is also mathematical proof:

Knowledge is Power. Time is Money.
And, as every engineer knows: Power=Work/Time
If Knowledge=Power and Time=Money, then
Solving for Money, we get

Thus, Money approaches infinity as Knowledge approaches zero, regardless of the work done. What this means is: The less you know, the more you make!

Ann Landers: On Product Safety!
Dear Ann Landers: The warning from "Careful in Colombia, MD.," to disconnect microwaves when not in use applies to other small appliances as well. Please print this letter. I wish I had seen one like it.
One afternoon when no one was home, my house sustained $42,000 worth of damage from a fire started by a defective toaster oven. The oven, which was only 3 years old, was not in use but was plugged in. The insurance company that paid the cost of rebuilding the house brought a claim against the toaster oven's manufacturer and was eventually reimbursed for the loss.
Please tell your readers to be cautious with appliances and unplug them when not in use.- Concerned in Capitola, Calif.
All of us take the safety of our kitchen appliances for granted. After all, they are UL listed and are manufactured by companies whose brand names are household words. However, failures do happen...and the consequences can be severe. If the appliance is a heating device, such as a coffee maker, toaster, toaster oven or breadmaker, a failure in the control circuitry could cause the appliance to fail in the maximum heat on condition, with disastrous results. MEi has conducted analysis in similar cases where small appliance have caused fires with extensive damage to property. So if you don't want us investigating a fire at your home, follow the advice of "Concerned in Capitola, Calif.," and unplug those small appliances when not in use. If you won't do it when not in use, at a minimum unplug them when you are on vacation or away from your home for more than a day.

The "What Is It?" Contest
The scanning electron microscope (SEM) is a powerful tool, capable of magnifications up to 180,000 times. It allows us to reveal information which is critical to metallurgical investigations, such as fracture modes and surface characteristics.
The SEM can also be fun to play with, because it allows one to view the surface of anything at high magnification with great depth of field. All of us have been amazed by the pictures of various insect parts, especially the eye of a fly.
In our contest, we take a look at an object on the SEM that should be familiar to all of you. In this issue our photographs show something that might be found in your kitchen, but you really wouldn't want to eat it. The photographs are two different types of the same thing. Good Luck.


Please fax, mail or e-mail us (don't call) with your answer. We will draw a winner from all correct entries received by June 6. The correct answer and the winner will be published in the next issue Of Materials Interest.
The prize is a $50 restaurant gift certificate, so put on your thinking caps.
Last issue, we had many correct entries, with many people having seen the photographs published in magazines like Popular Science in the past. The photographs show the surface of a compact disk. The pattern of "bumps and flats" are the 0's and 1's of the digital code.
Our winner, drawn at random from the correct entries, was Tom Hansel of Pacific Bearing in Rockford, Illinois. His efforts earned he and his wife a nice dinner at JMK Nippon Japanese Restaurant in Rockford. Pacific Bearing is the manufacturer of the Simplicity (TM) line of linear plane bearings, considered as the finest made. They also carry numerous other linear motion technology products. They sell direct to OEMs and through distributors, and their products are available throughout the world. You may have seen the Pacific Bearing adds in magazines like Machine Design and Design News, and they had a big display at the Design Engineering Show at McCormick Plaza in Chicago this spring.
Congratulations, Tom.

Next: 1999 Fall Newsletter