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One of the characteristic features of PbTe is an uncommon growth of bandgap with increasing temperature, which is quite opposite to the bandgap behavior of the semiconductors commonly used in electronics, for example, Si, Ge, GaAs, and InSb. This specificity allows one to increase the operating temperature of photodiodes fabricated using PbTe up to about 150 K. At the first stage of development, we prepared infrared (IR) photodiodes on the base of bulk single crystalline PbTe. To this end, the ingots with a diameter of about 40 mm were grown by the Czochralski technique. Then, the PbTe p–n junctions were fabricated by using indium donor diffusion to diffuse indium into the PbTe samples. Current–voltage and capacitance–voltage characteristics and spectral detectivity were measured over a wide temperature range and analyzed. The dark saturation current density at T = 100 K was of the order of 10−7 A/cm2. Finally, the unique solid-state multi-stage thermoelectric cooler operated at temperatures up to 150 K was developed. The present study would pave the way to creating a module for efficient photodetection in the mid-wave IR range combining two solid-state devices, namely, the p–n photodiode and thermoelectric cooler, while the latter supports the former. [ABSTRACT FROM AUTHOR]

The Bauschinger effect (BE) was originally defined as the phenomenon whereby plastic deformation causes a loss of yield strength restraining in the opposite direction. The Bauschinger effect factor (BEF), defined as the ratio of the yield stress on reverse loading to the initial yield stress, is a measure of the magnitude of the BE. The aim of the present work is to quantitatively evaluate the influence of plastic deformation on other material properties such as Young's modulus and Poisson's ratio for gun barrel steel, thus extending the definition of the Bauschinger effect. In order to investigate the change in this material's properties resulting from plastic deformation, several uniaxial tension and compression tests were performed. The yield stress and Young's modulus were found to be strongly affected by plastic strain, while Poisson's ratio was not affected at all. An additional result of these tests is an exact zero offset yield point definition enabling a simple evaluation of the BEF. A simple, triphase test sufficient to characterize the entire elastoplastic behavior is suggested. The obtained experimental information is readily useful for autofrettage residual stress field calculations. [DOI: 10.1115/1.2172962]

Presents a study which focused on the microstructure of crystals formed upon the crystallization of amorphous solids by investigating the double-shear theory and the transition of amorphous solids to crystals. Experimental details; Results and discussion; Conclusion.

Selective Laser Melting is one of the main methods of building metallic engineering components through Additive Manufacturing technology. Popular among materials for this method is the AlSi10Mg alloy which is thoroughly investigated by many researchers. Expanding the databases regarding the properties and behavior of this material will allow for more efficient and optimized implementation for this technology in various applications and industries. This work focuses on a systematic investigation of the impact properties of the AlSi10Mg alloy via Charpy V-notched tests and the impact energy that is absorbed while considering the effects of the high strain rates that are typical to the test. The properties are discussed for two building orientations (vertical and horizontal) under different conditions including the asbuilt condition, the typical T5 treatment and an additional modified T5 treatment. Residual stresses for the horizontal build direction are also discussed and the fracture mode dependency on the building direction is also shown. It was found that horizontally built specimens can absorb more impact energy compared to vertically built specimens, which conforms to the material properties of this alloy, favoring elongation for the X direction and separation within layers in contrast to the separation between weakly bonded layers of the Z specimens. [ABSTRACT FROM AUTHOR]

In today's additive manufacturing sector, one of the most popular areas is selective laser melting (SLM) due to its capability of producing geometrically complex metal parts directly from CAD model in a few short steps. Many studies have been reported on static mechanical properties of SLM components; however, dynamic properties of SLM components of different materials have not been thoroughly investigated. Only few papers have been published on the dynamic mechanical behavior, especially in the crack resistance of selective laser melted AlSi10Mg alloy. In the present study, the effect of loading rate, dynamic versus quasi static, on the fracture toughness of the as-built alloy (X and Z orientations) has been investigated. The experimental results revealed the inherently anisotropic behavior for loading rates where the Z orientation exhibited lower toughness compared to the x orientation. The dynamic loading by impact, resulted in a significant decrease of the toughness values up to about 50% compared to the quasi-static loading. This mechanical response was attributed to the increase in the yield stress which alters the state stress at the crack tip from the plane-stress to some extent of the mix-mode plane stress/strain. [ABSTRACT FROM AUTHOR]