2007 Volume 71 Issue 4 Pages 388-394
The structure and formation of superabundant vacancies in electroplated Ni64Fe36 alloy films have been studied by XRD and thermal desorption spectroscopy. The films, as deposited, consist of fine grains of ca. 10 nm in size, which, upon heating, start to undergo a gradual grain growth at ~600 K, and a rapid growth above ~670 K. The desorption of hydrogen occurred in seven stages; P0(385 K), P1(440 K), P2(560 K), P3(670 K), P4(960 K), P5(1170 K), and P6(>1270 K). P0 is attributed to desorption of H atoms on regular interstitial sites, P1~P2 and P4~P5 to H atoms trapped by vacancies, and P6 to hydrogen bubbles precipitated in the matrix. P3 and a desorption peak of CO+ (1100 K) are attributed to the decomposition of occluded C, H compounds. Binding energies of H in these trapped states are estimated, and possible configurations of these vacancy-H clusters are discussed.
