Study on Mechanism of Phase Forming in Ni+ Implantation into Ti6Al4V at Elevated Temperature

Recently, due to the prediction of the forming phase only focuses on the case which a simple metal ion implants into a single metal matrix, we will study that a simple metal ion is implanted into alloy matrix in this paper. The forming phases in Ni+implantation into Ti6Al4V at elevated temperature will be predicted by the effective heat of formation (EHF) model. The results show that the prediction is consistent with the experimental findings, the first-phase is TiNi with the most negative EHF, the second-phase is Ti2Ni which component concentrations of Ni limited element is lower and locates on the left in the Ti-Ni binary alloy phase diagram, and the TiNi3phase is not found in the experiment. Simultaneously, we explain correctly why the Ni-Al or Ni-V phases don’t generate in Ni+implantation into Ti6Al4V at elevated temperature.

Only Formation of ZrAl3 Phase Obtained by Self-Propagating Reaction from Zr-Al Elemental Powders

In this paper, the problem of ZrAl3compound obtained by self-propagating reaction as the only and favorable formation phase was considered. It shows that the ZrAl3phase could be synthesized by self-propagating reaction in Zr-Al system and was especially identified as the only phase by XRD, which was further confirmed by DTA. Using the theories of structural lattice of ZrAl3, Modified Effective Heat of Formation (MEHF) model, coupled with the First Nucleation Rule (FNR), the only formation of ZrAl3phase in Zr-Al system could be reasonably interpreted.

Synthesis and thermodynamic evaluation of intermetallic Mg-Ni/Mg-Cu nanoscale powders

Nanometer-sized intermetallic Mg-Ni and Mg-Cu compound powders were prepared by a physical vapor deposition method (arc discharge) and characterized by means of x-ray diffraction and transmission electron microscopy. Based on an empirical specific heat equation, the effective heat of formation and its temperature dependence were calculated to explain phase formation in nanoscale powders of the binary Mg-Ni and Mg-Cu systems. It is shown that theoretic calculations are in good agreement with the experimental observations.

Thin-film compound phase formation at Fe–Ge and Cr–Ge interfaces

Phase formation was studied in the Fe–Ge and Cr–Ge thin-film systems by means of Rutherford backscattering spectrometry and x-ray diffraction. In the Fe–Ge system, FeGe was the first phase to form while in the Cr–Ge system, Cr11Ge8 was found to form first. The results are compared with the predictions of the effective heat of formation model. Heats of formation were calculated using the Miedema model. The effect of the transformation enthalpy term ΔHtr, used to convert a semiconducting element into a hypothetical metallic one in the Miedema model, is also discussed.