Time-of-flight atom probe measurements on Ni3Al and Co3W

Abstract

In this study, a VG FIM100 was taken into operation, consisting of a field-ion microscope (FIM), a time-of-flight atom probe (TOFAP) and an imaging atom probe. A tungsten specimen was used to calibrate the conversion of flight times to m/n values. The resulting relative mass resolution of the TOFAP was calculated to be m/Deltam approximately 500 FWHM. In time-of-flight measurements of homemade boron-doped Ni-rich Ni(3)Al, a so-called ladder diagram was constructed from the evaporation data of a <001> pole. This ladder diagram revealed a very high degree of ordering in the alternating pure Ni and mixed Ni/Al planes: only 0.4% of the detected Al atoms were located on pure Ni planes. The number of null pulses to start a new plane was found to be much higher for Ni/Al planes (5 x 10(2)) than for Ni planes (1 x 10(2)). Moreover, the ladder diagram showed that boron was uniformly distributed through the matrix with nearly all boron found on pure Ni-planes. The suggestion that boron preferentially settles on these planes would be supported by reports of a strong Ni-B bond, since on Ni planes, B atoms can be accommodated on octahedral interstitial sites surrounded by only Ni atoms. Finally, we performed time-of-flight measurements on Co(3)W. The ion species observed in these measurements included a wide variety of WN(n)(2+) ions, with 0</=n</=9. Especially, the ions with odd n prevailed in this ion group.

Effects of solute Mg on grain boundary and dislocation dynamics during nanoindentation of Al–Mg thin films

“…However, the influence of solutes on the structure of such boundaries has not been experimentally identified. To this end, we are currently conducting a high-resolution TEM study on grain boundaries in Al and Al-Mg [27]. Another effect that may contribute to the pinning of special boundaries is solute drag on extrinsic grain boundary dislocations (EGBDs) as reported by Song et al [28], who showed that the dissociation rate of EGBDs in Al alloys is reduced by the addition of Mg.…”