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A deformation mechanism, rarely reported in Ti alloys, has been observed involving α/β interfacial and colony boundary sliding. This paper reports the initial characterization of this mechanism, involving a comparative study of the deformation behaviors of the new alloy (Ti–0.85Al–4.0V–0.25Fe–0.25Si–0.15O, in wt%) and an established α/β alloy. Both alloys exhibited slip steps on their surfaces. However, the new alloy may also deform by a mechanism which manifests itself as sliding at α/β interfaces and colony boundaries. This mechanism is consistent with the provision of significant ductility during very high strain rate testing, a property exhibited by the new alloy.

The strength of a commercial β‑titanium alloy was tuned by systematically controlling the size-scale of α precipitation via two-step heat treatments. While the first step annealing at 350 °C forms the precursor metastable ω phase, the subsequent annealing at 600 °C/1H resulted in fine-scale α precipitation. We find that annealing duration at 350 °C greatly impacts the α size-scale and, this consequently can be used to tune the ultimate tensile strength (UTS) from ~1 to 2 GPa. A combination of high volume-fraction of non-shearable super-refined α precipitates, coupled with their pyramidal arrangement, and a constrained β matrix leads to very high strength.

The compositional and order-disorder transition widths of γ′/γ interfaces in a Co–Al–W alloy have been established for the first time by coupling of aberration corrected high resolution scanning transmission electron microscopy and orientation-specific atom probe tomography. While the compositional width is approximately 2.5 nm, the order-disorder transition width is very sharp measuring 0.5 nm. A comparative study revealed that the γ′/γ interfaces, in a model Ni–Al–Cr alloy, are both compositionally and structurally diffuse with nearly the same width (~ 2.5–3 nm). These differences between the γ′/γ interfaces in Co and Ni-base alloys can impact the coarsening behavior of the ordered precipitates.

Electron microscopy, X-ray energy dispersive spectroscopy, and tomographic reconstructions were used to characterize a high entropy alloy predominantly composed of refractory elements. The intragranular microstructure was found to consist of a periodic two phase mixture, where a disordered bcc phase is aligned orthogonally in an ordered B2 phase. The phases were found to exhibit continuous lattice registry and an orientation relationship given by bcc// B2, {001}bcc//{001}B2. X-ray energy dispersive spectroscopy was used to determine the compositions of the phases, and spectral images were used in the tomographic reconstruction of the alloy to reveal the morphology and the elemental partitioning between phases.

A creep deformation mechanism in a polycrystalline nickel-base superalloy (Rene 88 DT) has been examined using crystallographic analysis and comparison between simulated and experimental high-resolution transmission electron microscopy (HRTEM) images. Confirmation of the magnitude of the Burgers vector of the partial dislocations involved in the creep deformation was critical in conclusively determining its nature. A new approach to determining a complex stacking fault was developed using superlattice image contrast from an experimental HRTEM image.

It has been recently shown that microtwinning is the principal deformation mechanism under certain creep conditions in several polycrystalline nickel-base superalloys. A creep model based on this mechanism is developed in this paper. Model parameters, supplied by microscopy and by atomistic calculations, are used to compare the model against experiment.

This paper reports a pioneering investigation of the orientation change of the α phase after recrystallization and the mode of transformation from the α to the β phase on heating above the β transus in the α/β alloy Ti–6Al–4V by in situ texture measurements done at room temperature, 800 °C, 1020 °C and again at room temperature using the HIPPO neutron time-of-flight diffractometer at the Los Alamos Neutron Science Center.