SECAT Newsletter Vol. 4, Issue 3

Secat
Aluminum WrapUp
Vol 4, Issue 3      
Aug/Sept, 2016



Secat News
Dr. Chenghe Xiao


Secat, Inc would like to wish Happy Anniversary to Dr. Chenghe Xiao! Dr. Xiao has been at Secat, Inc. for 15 years. He serves as the Technical Manager and supervises the lab and most technical matters. His strong background in physical metallurgy and failure analysis of aluminum serves him well to guide and support technical personnel.

 

#HeLovesAluminum


Featured Capabilities
The Electron Microscopy Center at UK
 
The Electron Microscopy Center at the University of Kentucky, located a short distance from Secat in Lexington, KY, recently acquired a state-of- the-art focused ion beam and scanning electron microscope (FIB-SEM) system. This instrument, a Helios NanoLab 660 made by FEI, offers a suite of characterization capabilities for advanced analysis of materials. The Electron Microscopy Center provides both
training and full characterization services to internal users and external customers.
The SEM and FIB are combined in a single chamber, and the SEM offers a spatial resolution better than 1 nm. In practice, this allows the imaging of features as small as 1-2 nm, even when the sample is non-conducting. Multiple detectors,
each of which generates different contrast and yields complementary sample 
information, can be selected for imaging. In addition to the traditional modes of 
secondary electron imaging and backscattered electron imaging, the system can produce images with ions or with filtered electrons (removal of stray electrons). It
is possible to obtain clear contrast between grains, simply due to crystallographic 
orientation.
The focused ion beam (FIB) portion of this system utilizes a gallium ion source to produce a narrow beam of ions that mill material from the sample surface, with
2.5 nanometer spatial resolution. At higher beam current, sample volumes up to 
10 or 100 microns in each dimension can be removed. Cross-sections can be easily milled into a sample surface, revealing interior regions for imaging and also analysis of chemistry or grain orientation. The x-ray energy dispersive 
spectrometer (EDS) has a large area detector that facilitates rapid chemical 
analysis of sample composition. Also, the electron backscatter detector (EBSD) 
determines orientation of grains within the sample, at a resolution down to 10-20 
nm.
The FIB-SEM system includes automated software for the acquisition of images/composition/orientation over
large sample areas. Analysis runs can be 
scheduled for overnight acquisition, generating maps that cover millimeter 
dimensions that still have high resolution.
A distinct advantage of the FIB-SEM is the ability to perform site-specific
characterization of specimen features. Once the overall sample surface has been surveyed, specific features can be selected for cross-sectional analysis. Moreover, thin foils can be milled from a particular site and extracted for analysis in the transmission electron microscope. This permits the characterization of specific grains, phases, inclusions, etc. The milling capabilities of the FIB-SEM also allow a cross-section to be successively milled in small steps, with imaging/analysis after each cross-sectional slice, after which the slices can be reconstructed to produce a three-dimensional tomograph that includes information throughout the analyzed volume.
Selected results for aluminum are presented below. Of course, these characterization techniques can be applied to all metals, alloys and other
materials. In fact, the ability to image at low beam voltage allows non-conducting 
materials to be analyzed without the need for sample coating.
High resolution imaging of the surface of an aluminum sheet sample.

 

Cross-section of an aluminum sheet sample (left); secondary electron (top right)
and backscattered electron (bottom right) images of the defect-rich subsurface.
 

 

FIB cross-section and EDS map of composition for the subsurface of an aluminum sample. The FIB was used to mill a cross-section at the region of interest (top left), and the chemical map revealed a layer rich in oxygen and magnesium just beneath the surface (top right). A composition depth profile across this region confirms its concentration and size (bottom right).
 

Thin foil extracted from an aluminum sample (left image) using the focused ion beam. The right image shows a transmission electron micrograph that reveals information through the sample thickness. A thin oxide region is visible at the top/right.
 
For more information, please contact Todd Boggess at
tboggess@secat.net or
859-514-4989.

PoDFA (Porous Disk Filtration Apparatus) Inclusion Identification & Quantification Analysis at SECAT

 
The metallurgical quality of cast aluminum plays an important role in the final product properties. How to
effectively clean and accurately assess the cleanliness of the aluminum melt at all stages of manufacturing is critical for metallurgists. PoDFA (Porous Disk Filtration Apparatus) is a complete solution to provide both qualitative information on the nature of inclusions and quantitative information on the various inclusions concentration in aluminum melt.This technology is ideal for process control and development as well as for product certification. It can help assess the effect of various operating practices on metal cleanliness. Secat provides PoDFA filter analysis for our customers to continuously improve their product quality and the efficiency of various refining practices.The PoDFA technique consists of filtering, under controlled conditions, a predetermined quantity of liquid aluminum through a very fine porosity filter disc. Inclusions of the melt are concentrated at the filter surface by a factor of 10,000. A liquid aluminum sample is taken from any locations/stage in the process line. The sample is poured into a PoDFA crucible and put on a small portable PoDFA sampling station. This station will create a vacuum to force the aluminum through the filter.An alternate to the PoDFA is the Prefil Footprinter which is available at Secat for testing of the liquid metal at customer sites. The main difference with the PoDFA unit is that it provides a real time graph of metal flow with time enabling the determination of how fast the metal flows through the filter. In simple terms, the faster the metal flows through the filter, the cleaner the metal.

When the metal is frozen, the filter along with the residual metal, is sectioned just below the filter/metal interface, mounted and polished before being analyzed under a microscope by a trained PoDFA metallographer at Secat.

PoDFA data allows the user to make a clear decision regarding the suitability of an individual production run for use in critical applications such as bright trim, can body stock, foil or lithographic sheet. For example, inclusion content is strictly controlled in aluminum can body stock, otherwise pinhole and/or tear-off defects can occur during the can making process in the presence of inclusions. Thus, can body stock makers would like to know how inclusions evolve at different stages in the process line.

Fig 1 shows an example of refining efficiency in an AA3XXX process line before holding furnace refining (HFR) and after filtering. The melt appeared very clean after the filter. Detailed quantitative evaluation results are shown in Table 1.

A second example for an AA3XXX alloy in Fig 2 shows graphite and aluminum carbide (Al4C3) with spinel like oxides before refining. Detailed quantitative data is shown in Table 2. The melt after refining was clean with minimal graphite and aluminum carbide.


 
(a) Before holding furnace refining, 100X (b) After the filter, 100X
1 – MgO; 2 – Spinel (MgAl2O4); 3 – Alumina; 4 – filter material
Fig 1: Optical images showing inclusions in AA3XXX sample
Before holding furnace refining (HFR) and after the filter.
Table 1: Metallographic Analysis Report for the AA3XXX alloy
Before holding furnace refining (HFR) and after filter
 

(a) Before holding furnace refining, 100X (b) After filter, 100X
1 – Graphite and aluminum carbide; 2 – Spinel like; 3 – filter material
Fig 2: Optical images showing inclusions in another AA3XXX sample
Before holding furnace refining and after the filter

Table 2: Metallographic Analysis Report for another AA3XXX alloy
Before holding furnace refining (HFR) and after filter
 
For more information, please contact Todd Boggess at tboggess@secat.net or 859-514-4989.



Person of Interest
Tom Dooley: Quality Assurance Manager
Tri-Arrows Aluminum, Inc.



I have worked in the aluminum industry for 28 years.  I have spent 25 years with Tri-Arrows 
Aluminum/Arco Aluminum as the Quality Assurance Manager and Technical Services Manager. 

Prior to coming to TAA, I worked for Metallurgical Services Company conducting R&D on 
aluminum can sheet.  I have a BS in Metallurgical Engineering from the Colorado School of 
Mines.

1) Give us a quick overview of your job. (Types of analysis you perform.)

My position at Tri-Arrows Aluminum is Quality Assurance Manager. I am involved with resolving

customer issues at beverage can and end plants. This work includes evaluating the possible cause for a 
problem and providing a corrective action to the customer.

2) What are some things that happen for you in a typical day at work?

A typical day at a customer’s plant involves reviewing current issues and determining if the aluminum or 
rolling defects are part of the problem. This involves inspecting the aluminum sheet and sending 
samples for evaluation at our plant or to Secat, Inc.

3) How does your job impact the markets you serve?

Problems at customer plants greatly impact their production of cans and ends. By solving these issues,
their efficiency increases.

4) How do you interact with Secat, Inc. and how does the relationship benefit you?

Secat’s reputation within our industry allows them to provide unbiased analysis of problems or defects.

5) Tell us something about yourself (outside of the industry) that people may not know.

I enjoy long distance running and I have also taken up scuba diving with my daughter.

 
#TomLovesAluminum

Aluminum Art

It’s a Sign


One of the beauties of aluminum is its recyclability and we’ve found an artist who goes far beyond the aluminum can, using road signs as his medium for design.

Boris Bally is a Swiss-trained metalsmith/designer working in Providence, RI where he maintains his small studio business, Bally Hu manufactured, LLC. “In the early 1990s, I explored this medium (Traffic Signs) and became the first designer to pioneer, produce and show this award-winning, iconic furniture, art and furnishings.” says Bally. There are now other furniture designers that have been inspired by his work.

Visit
www.borisbally.com to see more of this talented artist/designer’s work.

Recently, Bally was interviewed for the Smithsonian Institution, Archives of American Art: Oral History project, part of the Nanette Laitman Grant.

 

#BorisLovesAluminum
Don’t Forget to Connect with
Secat on Social Media!

 

CONNECT with Secat’s Company Profile on LinkedIn.
LIKE us on
FACEBOOK.
FOLLOW us on TWITTER: @SecatAluminum, #WeLoveAluminum

Check out our

 
We are talking about ALUMINUM, everyday! Join in the conversation!

 

#WeLoveAluminum
Having a problem with your aluminum manufacturing? 
 

 

Contact Secat – let us be your R&D resource. 
Call Todd Boggess at  

Stay Tuned for the next issue of 

Aluminum WrapUp,

 due out November, 2016

 

By | 2016-11-21T11:12:29+00:00 August 18th, 2016|Newsletter|Comments Off on SECAT Newsletter Vol. 4, Issue 3

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