Ozkan Gokcekaya

Extensive research on nature-inspired cellular metamaterials has globally inspired innovations using single material and limited multifunctionality. Additive manufacturing (AM) of intricate geometries using multi-materials provides additional functionality, environmental adaptation, and improved mechanical properties. Recently, several studies have been conducted on multi-material additive manufacturing (MMAM) technologies, including multi-materials, methodologies, design, and optimization. Howe

Additive manufacturing offers an exclusive way of anisotropic microstructure control with a high degree of freedom regarding variation in process parameters. This study demonstrates a unique texture formation in Inconel 718 (IN718) using a bidirectional laser scan in a laser powder bed fusion (LPBF) process for tailoring the mechanical properties. We developed three distinctive textures in IN718 using LPBF: a single-crystal-like microstructure (SCM) with a <110> orientation in the build directio

This is the first comprehensive study on the development of a cubic crystallographic texture in pure chromium (Cr) manufactured using laser powder bed fusion (LPBF) with different laser energy densities to alter its microstructure and high-temperature oxidation behavior. An increase in the laser energy density led to the formation of a strong crystallographic texture, which was preferentially oriented in the (100) plane, and there were microstructural improvements in the pure Cr. The grain size

The laser powder bed fusion (LPBF) of pure tungsten for the fabrication of near-fully dense components is challenging owing to the intrinsic properties of tungsten. In this study, routine, gas-atomized, and plasma-processed tungsten powder samples were characterized for their powder shape, size distribution, tapped density, and flowability, and then used to fabricate parts using identical LPBF process parameters to evaluate the influence of the powder characteristics on the metal densification a

This study developed a non-equiatomic Ti28.33Zr28.33Hf28.33Nb6.74Ta6.74Mo1.55 super-solid solutionized BioHEA using laser powder bed fusion (LPBF) to reach the full potential as BioHEA. We succeeded in significant suppression of elemental segregation, thus, resulting in a single crystalline-like texture by activating layer-to-layer epitaxial growth. Relatively low Young’s modulus was achieved in the single crystalline-like BioHEA. Moreover, LPBF-fabricated BioHEA exhibited significantly higher y

Processing of pure chromium (Cr) encounters substantial challenges due to its high melting point and intrinsic brittleness. Although laser powder bed fusion processing (LPBF) offers a novel processing approach by reaching the temperature required to melt pure Cr, the high ductile-to-brittle transformation temperature (DBTT) of pure Cr prevents the density of the as-built Cr component from reaching the level of industrial acceptance. This study focuses on raising the quality of the as-built pure

The metal-based 2D auxetic lattice structures hold the potential for multifunctional tasks in aerospace applications. However, the compression response of those manufactured by powder bed fusion process is underexplored. This study proposes a comprehensive comparison of in-plane quasi-static compression performance of 2D auxetic lattice structures, utilizing three designs (anti-tetrachiral (ATC), double arrow-headed (DAH), and tree-like re-entrant (TLR)), manufactured with stiff Ti6Al4V by the e

The 2D double arrow-headed (DAH) lattice structures, which are promising cellular structures for impact mitigation, remain relatively unexplored in terms of their compression response when manufactured using the powder bed fusion process with Ti6Al4V (Ti64) alloy. This study aims to investigate the effects of build orientation and beam scan speed of Electron Beam Powder Bed Fusion (PBF-EB) process on the energy absorption of 2D Ti64 DAH lattice structures. Additionally, potential microstructural

The ion nitriding behavior of AISI 316L austenite stainless steel was investigated at different nitriding times (2 h, 4 h, and 9 h) and temperatures (450 °C, 500 °C, and 550 °C). The structural characterization has been assessed by several considerations which can be listed: (i) the evaluation of phase distribution through Rietveld analysis of X-ray diffraction patterns and accompanying peak fitting process, (ii) hardness profile and related nitride layer thickness by microhardness and microscop

Abstract Inconel 718 alloy is difficult to machine using conventional methods due to its physical properties. Thereby, additive manufacturing (AM) of IN718 components with near-net shapes has been extensively studied. Even though AM processes provide shape and size accuracy, there is still the need for the machining of the AM-processed components to achieve the final shape of a component. Laser powder bed fusion (LPBF) has been successfully utilized to fabricate near-net shape IN718 components;

Ag-containing hydroxyapatite (HA) can reduce risks associated with bacterial infections which may eventually require additional surgical operations to retrieve a failed implant. The biological properties of HA in such applications are strongly affected by its composition in terms of dopants as well as Ca/P stoichiometry, which can be easily controlled by altering processing parameters, such as precursor concentrations. The objective of this in vitro study was to understand the effect of variatio