Accession Number : ADP004127

Title :   Photoacoustic Microscopy of Oxygen Contaminated Titanium Alloys,


Personal Author(s) : Thomas,R. L. ; Favro,L. D.

Report Date : JUL 1984

Pagination or Media Count : 12

Abstract : The photoacoustic microscope is a device which uses a chopped laser beam as a modulated heat source and an acoustic cell and a detector to measure the microscopic thermal properties of materials. The result is a micrograph of the variations of the near surface thermal properties of the sample. As such it is a useful device for observing defects and the near subsurface grain structure of materials. Such structure is expected to be affected by nonsubstitutional impurities such as oxygen in titanium. We have applied this technique to the five samples of titaniumn alloy. The samples were first machined flat and polished to remove the disturbed surface region and tool marks which were present when they were received. Individual photoacoustic micrographs were taken of each sample and then comparative photoacoustic micrographs were taken of pairs of samples within the same cell to eliminate systematic errors due to variations of cell properties. These micrographs indicated small differences in the microscopic structures in the various samples but these differences appear to be overwhelmed by the gross variations in grain structure apparently induced by the rolling processes, etc. Rather large variations in structure were observed from point to point in the same sample, making it difficult to make meaningful comparison between samples. Micrographs which indicate the differences and similiarities of the samples will be presented. (Author)

Descriptors :   *Titanium alloys, *Oxygen, *Contamination, *Microscopes, Laser beams, Grain structures(Metallurgy), Thermal properties, Graphics, Comparison, Subsurface

Distribution Statement : APPROVED FOR PUBLIC RELEASE