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Stern A.,Ben - Gurion University of the Negev | Aizenshtein M.,NRC Negev
Materials Science and Technology | Year: 2011

The magnetic pulse welding of Al-A1050 to Mg alloys was successfully performed, and the structural-mechanical properties of the interfacial bonding layer produced between dissimilar metals were studied. The morphology of the interface layer has a typical wavy pattern with an average thickness of 20 μm. Compositional microanalysis showed that the composition of the interfacial layer is Al-50 at-%Mg and is practically uniform, being a direct outcome of the local melting effect, intensive mixing of the melt and a rapid rate of solidification. The composition of the bonding layer corresponds to the Al supersaturated intermetallic β phase (Mg17Al12). The elastic modulus (and the hardness) of the interfacial layer was measured using the nanoindentation technique, and its value of 60±1.4 GPa is in good agreement with the value calculated from first principles in the literature (57.3 GPa) for the Mg17Al12 intermetallic phase. © 2011 Institute of Materials, Minerals and Mining.

Stern A.,Ben - Gurion University of the Negev | Shribman V.,Bmax Srl | Ben-Artzy A.,NRC Negev | Aizenshtein M.,NRC Negev
Journal of Materials Engineering and Performance | Year: 2014

Magnetic pulse welding (MPW) is a solid-state impact welding technology that provides metallurgical joints while exhibiting a negligible heat-affected zone. The MPW process is a high speed single shot welding technique used mainly for joining tubular components in a lap configuration and characteristic length scales of few millimeters to centimeters. It is similar in operation to explosive welding and shares the same physical principles. The nature of bonding in MPW is not sufficiently understood yet and some controversial explanations are reported in the literature. The two major ideas are based on either solid state bonding or local melting and solidification. The present work summarizes our current understanding of the bonding mechanism and the structure in various similar and dissimilar metal pairs joined by MPW. © 2014, ASM International.

Barzilai S.,NRC Negev | Hayun S.,Ben - Gurion University of the Negev
Journal of Materials Science | Year: 2015

Tantalum–titanium alloys have widespread potential in biomedical applications due to their superior biocompatibility, favorable mechanical properties, high corrosion resistance, and ability to exhibit shape memory behavior. However, this system is plagued by processing difficulties due to significant differences in melting temperatures, specific weights, and vapor pressures of Ta and Ti. In the present study, mechanical alloying (MA) using high‐energy ball milling of Ti–xTa (where x = 50, 60, 70, and 85 wt%) was investigated. The alloyed powders were characterized by X-ray diffraction, electron microscopy (SEM and TEM), and differential scanning calorimetry. It was established that α-Ti (hcp) gradually dissolves into α-Ta (bcc), with the alloyed particles becoming chemically homogeneous as a bcc structure. This structure corresponds to a meta-stable phase and should decompose to yield two solid solutions, Ti-rich hcp and Ta-rich bcc. To overcome this thermodynamic preference, MA-generated Ta–Ti bcc solid solution powders possess relatively high internal strain energy. © 2015, Springer Science+Business Media New York.

Aizenshtein M.,NRC Negev | Froumin N.,Ben - Gurion University of the Negev | Frage N.,Ben - Gurion University of the Negev
Journal of Materials Engineering and Performance | Year: 2012

TiB 2 among other borides like ZrB 2 and HfB 2 represents a unique class of ceramics, which displays good wetting by liquid metals, such as Cu and Au, without chemical interaction that may be detected by conventional characterization techniques. The nature of the wetting in these systems is commonly attributed to the "metallic-like" character of borides. In this study, improved wetting of TiB 2 by Cu and Au (50° and 15°, respectively) was confirmed and evidence of a limited chemical interface interaction was observed using TEM analysis. Moreover, it was shown that the addition of B to Au and Cu improves wetting. It was suggested that not only "metallic-like" character of TiB 2 but also the chemical interaction stands behind good wetting in these systems. © ASM International.

Ben-Galim Y.,Ben - Gurion University of the Negev | Wengrowicz U.,NRC Negev | Raveh A.,Advanced Coatings Center at Rotem Industries Ltd. | Orion I.,Ben - Gurion University of the Negev
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2014

A new approach for neutron detection enhancement to scintillator gamma-ray detectors is suggested. By using a scintillator coupled with a boron carbide (B4C) disc, the 478 keV gamma-photon emitted from the excited Li in 94% of the 10B(n,α)7Li interactions was detected. This suggests that the performance of existing gamma detection systems in Homeland security applications can be improved. In this study, a B4C disc (2 in. diameter, 0.125 in. thick) with ∼19.8% 10B was used and coupled with a scintillator gamma-ray detector. In addition, the neutron thermalization moderator was studied in order to be able to increase the neutron sensitivity. An improvement in the detector which is easy to assemble, affordable and efficient was demonstrated. Furthermore, a tailored Monte-Carlo code written in MATLAB was developed for validation of the proposed application through efficiency estimation for thermal neutrons. Validation of the code was accomplished by showing that the MATLAB code results were well correlated to a Monte-Carlo MCNP code results. The measured efficiency of the assembled experimental model was observed to be in agreement with both models calculations. © 2014 Published by Elsevier B.V.

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