Intern: R. William Hunter II

Mentor: Damon D. Brink

Faculty Sponsor: Dr. Carlos Levi

Title of Internship: The Effect of Interlayer Yield Strength on the Strength of Metal-Matrix Composite Joints

I am a Bio-science student at Santa Barbara City College. I interned in the Materials Processing Lab of the Department of Engineering where my mentor was Damon Brink. Damon is a graduate student who works primarily with experimental materials called Metal Matrix Composites (MMCs), specifically MMCs made of aluminum alloys reinforced by very thin, continuous fibers of alumina.

MMCs of this sort are strong, stiff, and light. One can imagine, however needing to join two MMCs together, perhaps by bonding them with an interlayer of the same aluminum alloy which forms the matrices of the composites. Such a joint is weaker than the MMCs it joins, so under sufficient stress, failure takes place at the joint. Damon's work focuses on improving the strength of these bonded joints.

Damon taught me many of the techniques he uses in his investigations as we sought to determine whether a joint can be made stronger by adding magnesium to the interlayer alloy, thereby increasing its yield strength. I learned that the more magnesium was contained within an otherwise pure sample of aluminum, the more stress it took to permanently deform it (reach the sample's yield strength). Our tests provided Damon with baseline information which he can utilize in ongoing tests to determine if interlayers with high yield strengths due to magnesium content make stronger joints.

During the 8 week period I learned the fundamentals of the mechanical Principles at work in these sort of tests, as well as how to make a MMC that is suitable for testing. I prepared the filters for casting, took measurements, and prepared samples for testing. Tensile tests were conducted on an Instron tensile testing machine.

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