University System of Maryland

U.S. Government as Represented by the Director, National Security Agency

Ronald W Armstrong

John J Lesko

Warren T Beard, Jr

Disclosed is a method and apparatus of indentation testing of variable types of specimens which includes mounting an indenter member onto a thermally expandable member, mounting the specimen to be tested on a pedestal, loading the specimen with the indenter member by thermally expanding the thermally expandable member and measuring applied force to and displacement of the specimen so as to determine the hardness or other material properties of the specimen. The indenter member is thermally insulated from the thermally expandable member prior to thermally expanding the thermally expandable member. The thermal expansion driven indentation system in the present invention allows for controlled application of precise and continuous reproducible loads to produce stress-strain plots. Continuous indentation testing with this system has yielded results which correlate well to Rockwell fixed load hardness tests on standard test blocks. Further, efforts in drawing relationships with tensile results have shown support for the use of continuous indentation testing for the generation of local material properties.

Thermal expansion driven indentation stress-strain system

An improved asymmetric crystal topography x-ray imaging system employing a ine focus horizontal line source of x-rays and a crystal monochromator used in a compression mode. Relatively large horizontal and vertical dimensions of the monochromating crystal allow imaging of larger areas of imperfect crystals than previously possible, without adversely affecting image resolution. The high resolution two-dimensional images are a direct consequence of our method of controlling the probe beam divergences. An appreciably enhanced and useful intensity of monochromatic x-rays is obtained over that available with prior asymmetric crystal topography systems.

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Edgewater, MD, United States of America

Ronald W Armstrong