AN X-RAY STUDY OF RESIDUAL STRESSES AND BENDING STRESSES IN FREE-STANDING Nb/Nb_5Si_3 MICROLAMINATES

摘要

Asymmetric X-ray diffraction was used to quantify residual stresses in Nb/Nb_5Si_3 microlaminates that were sputter deposited and then annea1ed at l200deg. C for 3 h. The residual stresses are attributed to a mismatch in the thermal expansion coefficients for the Nb and Nb_5Si_3 phases, and can rise as high as 300 MPa on cooling from l200deg. C. Sizable (＞ 500 MPa) bending stresses were also detected in microlaminates that were curved after annealing and then were flattened for X-ray analysis. The residual stresses in the Nb laminates were quantified using an improved anisotropic elastic analysis that accounts for the strong (ll0) texture in these layers. The stresses in the Nb_5Si_3 laminates were quantified using an isotropic elastic analysis that accounts for both residual stresses and bending stresses.