Decomposition of the interstitial solid solution Pd(B)

The decomposition at 628 K of a Pd(B) solid solution containing 6 at.% boron was analyzed by use of, primarily, X-ray diffraction. A structure model was used to simulate the X-ray diffraction-line profiles. The decomposition is described as the precipitation of a boron-poor face-centered cubic (fcc) phase in the parent fcc phase gradually enriching in boron. The experimentally determined width of the miscibility gap is different from previous experimental results, but agrees with theoretical data obtained on the basis of the quasi-chemical approximation. Further, the microstrain in the decomposed state was measured and compared with that of the initial, quenched supersaturated solid solution; good agreement is observed between results obtained from X-ray diffractometry and transmission electron microscopy. (orig.)