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Residual Stress Determination in Al2O3/SiC (Whisker) Composites By X-Ray Diffraction

Published online by Cambridge University Press:  06 March 2019

Paul Predecki ,
Alias Abuhasan  and
Charles S. Barrett
Paul Predecki
Affiliation:
University of Denver Denver, CO
Alias Abuhasan
Affiliation:
University of Denver Denver, CO
Charles S. Barrett
Affiliation:
University of Denver Denver, CO
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Abstract

Residual strains and stresses were determined in both phases of a hot pressed α-Al2O3 composite containing 25 wt % β (cubic) SiC whiskers using conventional x-ray diffraction and profile analysis. Both phases in this composite were randomly oriented as confirmed by back reflection pinhole photographs. The reflections found most useful with Cu Kα radiation were: 511 + 333 for β-SiC at -134° 2θ and 146 for α-Al2O3 at -136° 2θ. The peak shift and broadening observed in these reflections, relative to the starting powders, were largely due to the two phases mutually constraining each other elastically. This was confirmed by the reversal of the peak shift and most of the broadening in the SiC reflections when the Al2O3 matrix was etched away. Using the method of Cohen and Noyan, it was found possible to separate the macrostresses from the microstress components in each phase. The microstresses were largely hydrostatic; of the order of 895 MPa (130 ksi) compressive in the whiskers and 370 MPa (54 ksi) tensile in the matrix. The macrostresses were ~79 MPa (11.5 ksi) tensile.

Type
III. X-Ray Stress/Strain Determination, Fractography, Diffraction, Line Broadening Analysis
Information
Advances in X-Ray Analysis , Volume 31: Thirty-Sixth Annual Conference on Applications of X-ray Analysis, August 3-7, 1987 , 1987 , pp. 231 - 243
Copyright
Copyright © International Centre for Diffraction Data 1987

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