HAYNES 230 is a solid solution strengthened, face centered cubic (FCC), nickelbased superalloy, with a small amount (1–5 vol. %) of semi-coherent FCC carbides. Neutron diffraction experiments were performed to study the interaction of the carbides with the matrix during tensile and compressive loading. The behavior of the elastic lattice strains during in situ loading clearly showed a tension-compression asymmetry. Although the volume percentage is small, the interaction between the carbides and the matrix had a significant effect on the load sharing. In compression, the carbides began load sharing at the macroscopic yield point, while the tension test suggests no load sharing. Debonding at the carbide-matrix interface is proposed to explain the lack of load sharing during the tensile loading based on the disparities observed between the experimental results and the finite element models.

Zr-based alloy ingots with nominal compositions of Zr52.5Cu17.9Ni14.6Al10.0Ti5.0 (at.%), Vitre-loy 105, were isothermally annealed below the glass-transition temperature at 630 K for 10, 20, 30, 40, and 60 minutes in vacuum to obtain samples with various states of structural relaxation and compared to the as-cast state. Structural studies were performed using time-of-flight neutron diffraction followed by pair distribution function (PDF) analyses. Differential scanning calo-rimetry (DSC) was conducted to examine changes in the specific heat, which were correlated to the amount of structural relaxation in the various samples. These samples exhibited increasing structural relaxation with longer annealing times, which was evidenced in the atomic PDF. Relaxation related to the exothermic peak results in changes in the PDF that are consistent with the elimination of short and long inter-atomic distances. Further annealing led to rearrangements in the second atomic shell that may be related to local phase separation.

Quasi-phase matching in AlxGa1−xAs heterostructure optical waveguides can be used for efficient second-harmonic (SH) generation. The efficiency of these devices depends on the linear and nonlinear optical properties of the component materials. We present measurements of the SH susceptibility variation in AlxGa1−xAs with Al concentration, for fundamental light at λ = 1.06 μ. The measured SH susceptibility decreases by an order of magnitude as the Al concentration is varied from x = 0 to x = 0.97. These measurements are used to evaluate the SH generation efficiency of AlxGa1−xAs heterostructures as the structural and material parameters are varied.