R. Ipek

Development of Ti-Nb-Zr alloys with high elastic admissible strain for temporary orthopedic devices.

A new series of beta Ti-Nb-Zr (TNZ) alloys with considerable plastic deformation ability during compression test, high elastic admissible strain, and excellent cytocompatibility have been developed for removable bone tissue implant applications. TNZ alloys with nominal compositions of Ti-34Nb-25Zr, Ti-30Nb-32Zr, Ti-28Nb-35.4Zr and Ti-24.8Nb-40.7Zr (wt.% hereafter) were fabricated using the cold-crucible levitation technique, and the effects of alloying element content on their microstructures, mechanical properties (tensile strength, yield strength, compressive yield strength, Youngs modulus, elastic energy, toughness, and micro-hardness), and cytocompatibilities were investigated and compared. Microstructural examinations revealed that the TNZ alloys consisted of β phase. The alloy samples displayed excellent ductility with no cracking, or fracturing during compression tests. Their tensile strength, Youngs modulus, elongation at rupture, and elastic admissible strain were measured in the ranges of 704-839 MPa, 62-65 GPa, 9.9-14.8% and 1.08-1.31%, respectively. The tensile strength, Youngs modulus and elongation at rupture of the Ti-34Nb-25Zr alloy were measured as 839 ± 31.8 MPa, 62 ± 3.6 GPa, and 14.8 ± 1.6%, respectively; this alloy exhibited the elastic admissible strain of approximately 1.31%. Cytocompatibility tests indicated that the cell viability ratios (CVR) of the alloys are greater than those of the control group; thus the TNZ alloys possess excellent cytocompatibility.

An investigation of the microstructure and mechanical properties of B4C reinforced PM magnesium matrix composites

Due to their excellent properties such as high specific stiffness, strength/weight ratio, and wear resistance, metal matrix composites (MMCs) with particulate reinforcement and related manufacturing methods have become important research topics in recent years. Magnesium MMCs are materials that are commonly used for fabrication of light-weight functional components. Magnesium MMCs that are reinforced with various fractions of B4C (3, 6, and 9 wt.%) were fabricated by powder metallurgy (PM) technique using a sintering cycle in a vacuum furnace at 590°C for 9 h. A qualitative analysis of X-ray diffraction (XRD) patterns indicated the formation of Al2O3, MgO, and MgB2 phases in the structure of Mg/B4C MMCs. The sintered density of the MMCs decreased with an increase in the amount of B4C addition. The hardness of the MMCs was found to be higher than that of unreinforced Mg. The compressive test results also showed a significant effect of 3 wt.% B4C content on the compressive strength of magnesium MMCs manufactured by the PM technique.

Investigation of the wear resistance and microstructure of Al/SiC metal matrix composites as a function of reinforcement volume fraction and reinforcement to matrix particle size ratio applying artificial neural network

Abstract In this study, the influences of reinforcement volume fraction and the ratio of the reinforcement particle size to the matrix particle size on the wear behaviour of Al/SiC metal matrix composites were investigated by use of a model function obtained from an artificial neural network. Hardness and ball-on-disc wear tests were applied to Al/SiC composites manufactured via a powder metallurgy method. The results indicate that as the reinforcement volume fraction and the ratio of the reinforcement particle size to the matrix particle size increase, the wear loss decreases except in two cases; in the first case (vol.% ≤ 7.5), as the ratio of the reinforcement particle size to the matrix particle size rises, the wear loss increases and then decreases. In the second case, the decreasing trend of wear loss at high values of volume fraction (≥ 15%) declines and then increases where the value of the reinforcement to the matrix particle size ratio is about 1.

Effect of Ca and Zn additions on the mechanical properties of Mg produced by powder metallurgy

Magnesium and its alloys are among important research topics in view of their excellent biocompatibility.In this study mechanical and microstructure properties of hot sintered Mg-Zn-Ca alloys were studied.The effects of the addition of different amounts Ca and Zn were added to the base material has been processed by powder metallurgy method.resulting microstructures densities and compression test behaviors of the Mg-based alloys were studied.Visual inspection using SEM (Scanning Electron Microscope) analyses indicates that the microstructure of the composite is also greatly effected by these parameters. In addition, EDS (Energy Dispersive X-Ray Spectroscopy) analyses were performed for reliable determination of the chemical composition.

Microstructure and mechanical properties of Zn-Mg alloys as implant materials manufactured by powder metallurgy method

Currently some biomaterials, especially Zn and Mg alloys and related manufacturing methods are among important research topics due to their suitable biocompatibility, mechanical and corrosion properties. Zn Mg alloy has been processed by Mechanical Alloying method. Hot sintering was conducted at 410°C under argon atmosphere. Resulting microstructures densities and hardness test behaviors of the Zn-based alloys were studied.Visual inspection using SEM (Scanning Electron Microscope) analyses indicates that the microstructure of the composite is also greatly effected by these parameters. In addition, EDS (Energy Dispersive X-Ray Spectroscopy analyses were performed for reliable determination of the chemical composition.

Characterisation of magnesium matrix composite reinforced with SiC particulates manufactured by powder metallurgy method

Particle reinforced magnesium metal matrix composites (MMCs) and related manufacturing methods are among important research topics because of their low density, high specific stiffness, strength and wear resistance. SiCp/Mg composites are commonly used materials for fabrication of light-weight functional components. Magnesium powders with mean size of 69 mm were used as raw material while reinforcement material was selected as SiCp with the average particle size of 84 mm. Different amounts of SiCp (3, 6, and 9 wt. %) were added to the magnesium matrix and the composite materials were sintered in a vacuum furnace at 590°C. Structural characterisation of the produced composites was performed using several techniques such as scanning electron microscopy (SEM) and X-ray diffraction. The green density of the composite materials increased with SiCp addition. The hardness of the composites was found to be higher than the pure Mg. Reinforcement with 9 wt. % SiCp showed significant increase in the compressive stre...

An investigation of WEDM process parameters on the surface roughness of Al/B4Cp metal matrix composites

The purpose of this study is to define the effects of wire electrical discharge machining (WEDM) process parameters on surface roughness for Al/B4Cp metal matrix composites (MMCs) having different amounts of reinforcement particle (3, 6, and 12 wt.%). Totally nine experiments were performed according to the experimental design method conducted by Taguchi L9 orthogonal array on Al/B4Cp MMC samples to determine the effect of WEDM process parameters on the surface roughness. The particle reinforcement amount (wt.%) is the most dominant factor (60.69%) on the surface roughness and it is followed by pulse on time (36.28%) and wire feed (1.49%), respectively. The surface roughness value taken from confirmation experiments and predicted value is 5.26μm, 5.37μm respectively.