Nadia Kouraytem

• Doctor of Philosophy
• Assistant Professor at Utah State University

Laser powder bed fusion (LPBF) is an additive manufacturing process that has gained interest for its material fabrication due to multiple advantages, such as the ability to print parts with small feature sizes, good mechanical properties, reduced material waste, etc. However, variations in the key process parameters in LPBF may result in the instan...

Nearly all energy technologies utilize heat exchangers and recuperators within the power cycle. To further improve the cost-effectiveness of recuperators, costly high-temperature Inconel 625 superalloy was substituted with a more affordable stainless-steel 316 L to be used at the low-temperature side of the heat exchanger. Bimetallic samples for an...

Metal additive manufacturing is a disruptive technology that is revolutionizing the manufacturing industry. Despite its unrivaled capability for directly fabricating metal parts with complex geometries, the wide realization of the technology is currently limited by microstructural defects and anomalies, which could significantly degrade the structu...

Metal additive manufacturing (AM) presents advantages such as increased complexity for a lower part cost and part consolidation compared to traditional manufacturing. The multiscale, multiphase AM processes have been shown to produce parts with non-homogeneous microstructures, leading to variability in the mechanical properties based on complex pro...

Solidification or hot cracks are commonly observed defects in a number of metal alloys and may lead to deterioration of additively manufactured parts quality. In this study, ultra-high-speed x-ray radiography experiments enable the observation and characterization of bundles of hot-cracks that form in monobloc AA6061 substrate. The crack bundles ar...

The aim of the current study is to investigate the suitability of a solutionizing recrystallization (RC) heat-treatment to improve the yield strength of laser powder-bed fusion (L-PBF) Inconel 718 (IN718), while decreasing deformation anisotropy under uniaxial compression. Scanning electron microscopy measurements show an increase in grain size, de...

The microstructures of additively manufactured (AM) metal components have been shown to be heterogeneous and spatially variable when compared to conventionally manufactured counterparts. Consequently, the mechanical properties of AM-metal parts are expected to vary locally within their volume. For AM structural components intended to operate in ext...

Laser-induced keyholing occurs in additive manufacturing and welding processes, but the keyhole dynamics have not been well understood. A multiphase and multiphysics numerical model is used to predict the keyhole shapes recorded in the experimental observations and to predict transient and nonuni-form distributions of laser absorption, temperature,...

The microstructure of additively manufactured (AM) metals has been shown to be heterogeneous and spatially non-uniform when compared to conventionally manufactured metals. Consequently, the effective mechanical properties of AM-metal parts are expected to vary both within and among builds. Here, we present a framework for simulating process–(micro)...

Ultra high-speed imaging is used to investigate the vapor explosion when a drop impacts onto a high-temperature pool. The two liquids are immiscible, a low boiling-temperature perfluorohexane drop, at room temperature, which impacts a high boiling-temperature soybean-oil pool, which is heated well above the boiling temperature of the drop. We obser...

We investigate the impact penetration of spheres into granular media which are compositions of two discrete size ranges, thus creating a polydisperse bimodal material. We examine the penetration depth as a function of the composition (volume fractions of the respective sizes) and impact speed. Penetration depths were found to vary between δ=0.5D0 a...

We use high-speed video imaging to investigate vapor explosions during the impact of a molten Field's metal drop onto a pool of water. These explosions occur for temperatures above the Leidenfrost temperature and are observed to occur in up to three stages as the metal temperature is increased, with each explosion being more powerful that the prece...