X-ray diffraction determination of residual stresses in functionally graded WC–Co composites

• X-ray diffraction was used to determine the thermal residual stresses that develop in a functionally graded WC–Co composite. Stresses were measured in both WC and Co phases at various depths. Pole figures were obtained in order to determine optimal sample orientations that provided adequate intensity for measurements in the Co phase. For WC, the in-plane compressive residual stresses varied approximately between −300 and −500 MPa with depth below the surface. For the low volume fraction Co phase, the tensile residual stresses were approximately 600 MPa. The microstresses in the graded zone were attributed to the thermal mismatch between the WC and the Co phase during cooling from the liquid phase sintering temperature (1450 °C). The microstresses determined were in reasonable agreement with a prediction using Eshelby theory. The compressive macrostresses were attributed to the compositional gradient, a result further substantiated by the fact that no significant macrostresses were measured in a comparable homogeneous sample, i.e., without the compositional gradient. Thus, varying compositional gradients in WC–Co composites during fabrication can be expected to directly influence the macrostress component of the overall residual stress state.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Annan materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Other Materials Engineering (hsv//eng)

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TECHNOLOGY

TEKNIKVETENSKAP

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