Micromechanical Deformation

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9623808 Li The purpose of this project is to examine several techniques that can be employed in studying micromechanical deformation. Included within this group are the atomic force microscope, continuous indentation testing, the impression creep machine, and the scratch tester. Continuous indentation testing experiments are employed as a new technique to determine the adhesion strength between a deposited thin film and the substrate, as well as measuring Young's modulus and PoissonOs ratio of the film itself. Impression creep machine tests of grain boundaries and triple junctions in zinc are analyzed. Scratch testing of glass and polymers is performed to understand the stick/slip process. The atomic force microscope looks at shear bands in amorphous metals (with a magnetic indenter) as well as micro shear bands and crazes in polymers. Continuous indentation testing of amorphous metals on the wheel side and the air side are compared. Theoretical analysis involves finite element computation, analytical methods, molecular dynamics and modeling of critical steps in all of the tests. The studies are aimed at answering questions associated with the employment of these techniques and the micromechanical deformation behavior of the selected materials. %%% The results should impact techniques used for micromechanical measurements, polishing and grinding of glasses, and improved adhesion of thin films and coatings to substrates. ***