Theoretical Analysis on Fully Differential Cross-Sections for C^6＋ Single Ionization of Helium

The four-body model has been used to calculate the fully differential cross-sections （FDCS） for the single ionization of helium by 100 MeV/amu Ca^＋ impact in geometries. By comparing with experimental data and other theories, we find the results of four-body model are in very good agreement in the scattering plane, but poor agreement out of the scattering plane. Accordingly, the contributions of different scattering amplitudes to FDCS are analyzed. It is found that the cross sections due to the interference of the scattering amplitudes between projectile-target nucleus interaction and projectile-ejected electron interaction almost tend to experimental results around the recoil region in geometries. In particular in the perpendicular plane, the cross section originating from interference of the scattering amplitudes between projectile-target nucleus and projectile-ejected electron interactions yields an experimental double-peak structure in the angular distribution. However, this feature could not be presented by the interference of the three amplitudes. Thus, the failure of the fourbody model predicting the feature in this geometry may be attributed to an inappropriate weighting of the three amplitudes.

Evolution of microstructure and intervariant boundaries ofαphase in electron beam melted and heat-treated Ti-6Al-4V alloy

It is important to understand the correlation between grain morphology and intervariant boundaries of theαphase after heat treatment belowβtransus of the electron beam melted(EBMed)Ti-6 Al-4 V alloy.Scanning electron microscopy(SEM)and electron backscatter diffraction(EBSD)analysis have shown about 99%αphase and 1%βphase in the heat-treated samples when the temperature rises to 950℃.Four distinct types ofαgrain morphology have been found:allotromorphousα,relatively coarseαplate,large precipitationαand granularα.A single peak of the intervariant boundary with the misorientation of 60°/[1120]associated with Burgers orientation relationship(OR)was found in the allotromorphousαcolony.Multiple intervariant boundaries mixed with a fraction of general high-angle grain boundary(GHABs,not Burgers OR)were present in the relatively coarseαplate colony.Almost only low-angle grain boundaries(LABs)with the misorientation of<5°were found in the large precipitationαgrains.βphase tends to distribute around the boundaries of relatively coarseαplates.It suggests that different formation mechanisms are involved in the distinct types ofαgrain morphology.