Use of polarization in imaging the residual stresses in polycrystalline alumina films

✍ Scribed by Derek J. Gardiner; Michael Bowden; Samuel H. Margueron; David R. Clarke

• Book ID: 103998162
• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 785 KB
• Volume: 55
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2007.01.044

✦ Synopsis

Residual and applied stresses modify the characteristic R-line luminescence from trace amounts of Cr 3+ incorporated in aluminum oxide. This piezospectroscopic effect has been extensively used to measure, and image, stress distributions in a variety of aluminum oxides, including those formed by the thermal oxidation of aluminum-containing alloys. One drawback until now has been that the shift in the luminescence frequency is dependent on the mean stress rather than the individual stress components. In this work, we show that the principal stress directions and their magnitude can be obtained by combining the ratio of the R 2 and R 1 peaks as a function of collection polarization with the measured R 2 frequency shift. This is illustrated with images recorded from regions of a thermally grown oxide in which a narrow strip of the oxide has been isolated to produce regions of varying principal stresses and directions.