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IN718 is a Ni-based superalloy usually manufactured by conventional processes such as wrought or casting. However, recently additive manufacturing (AM) technologies, such as Powder bed fusion (PBF), are used to produce IN718 parts. Heat treatments, also designed for conventional processes, are usually used in AM parts to improve mechanical properties. Unlike traditional techniques, AM processes involve rapid cooling rates, large thermal gradients, and multiple reheat cycles, which might cause high residual stresses and elemental segregations in the printed parts affecting their final mechanical properties. In this work, a detailed comparative study of microstructural features was carried out in both wrought-and PBF-produced IN718. It was found differences in size, shape, and location of MC carbides. According to experimental results and the phase fraction diagram obtained from Thermo-Calc, these MC carbides cannot be dissolved in a conventional solution heat treatment. In consequence, these carbides continue their evolution during complete aging heat treatment, affecting the material hardness. Nevertheless, similar hardness in the wrought and AM sample was obtained after applying a modified aging treatment proposed in this work.

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Photo-carrier radiometry (PCR) has been used to study the distribution of impurities and the lattice damage in silicon-doped gallium arsenide in a noncontact way. The results from the PCR study are correlated with Hall effect measurements. Samples for this study were grown by molecular beam epitaxy. Of all possible parameters that can be manipulated, the silicon effusion cell temperature was the only one that was varied, in order to obtain samples with different silicon concentrations. The distribution of impurities was obtained by scanning the surface of each sample. The PCR amplitude and phase images were obtained as a function of the x-y position. According to the PCR images, it is evident that the impurities are not uniformly distributed across the sample. From these images, the average value of the amplitude and phase data across the surface was obtained for each sample in order to study the PCR signal behavior as a function of the silicon effusion cell temperature.

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