Microcantilever bend testing and finite element simulations of HIP-ed interface-free bulk Al and Al–Al HIP bonded interfaces

Abstract

We report on the strength of Al–Al interfaces and the effects of chemical segregation and interfacial void formation on bond strength using microcantilever bend testing. Interfaces are synthesised via hot isostatic pressing. Microcantilevers of several nominal dimensions were fabricated via focused ion beam and deformed in a nanoindenter. We find increased cantilever strength as a function of decreasing sample size, with a linear dependence of the yield strength on the inverse square root of the length scale characteristic to the cantilever cross-section. The presence of pores and chemical segregation decreases the yield strength of the material by 17% and the accommodated strain energy by 10–15% for strain values in the 6–12% range.     

Bestimmung der Rohdichte groβflächiger Betonbauteile mit γ-Strahlen

Bei Bauteilen aus Beton, die als Auβenwandelemente verwendet werden, splelt die Rohdichte, infolge ihres entscheidenden Einflussees auf die Wärmeschutzeigenschaften, eine wichtige Rolle, Bisher existiert keine zerstörungsfreie Prüfmethode, die es gestattet, die Homogenität und die Rohdichte groβflächiger Bauteile zu kontrollieren. Durch den Einsatz des γ-Durchstrahlungsverfahrens geligt es, die Rohdichte mit einen relativen Fehler kleiner als±3% zu ermitteln. die Meβfehler, die sich durch Änderung der Geometrie der Meβanordnung ergeben können, sowie verschiedene in der Praxis erprobte Meβeinrichtungen werden behandelt.     

Diffusion and precipitation phenomena across layer interfaces in a roll bonding composite of Al(Si) and Al(Cu)

Layered composite structures can be generated in metallic sheets by roll bonding of dissimilar metals/alloys. In this investigation, heat treatable (Al(Cu)) and non-heat treatable (Al(Si)) aluminium alloys are roll bonded in sheet form. Large hardness differences between layers poses significant bonding challenges in the form of multiple necking within the hard Al(Cu) layers. For successful processing, it is vital to choose the candidate materials in a state of marginal hardness differences during rolling, but being capable of altering properties through subsequent heat treatments. Atomic diffusion takes place during heat treatment of the composite sheet and results in gradual hardness variation across sheet thickness. The Al(Cu) layers contribute to strength, whereas the Al(Si) layers provide protection from corrosion/wear-related degradation in the newly developed hybrid sheet. The overall mechanical properties of the heat-treated composite fall between the base alloys. The bonding interfaces are noted as the potential spots for initiating failure.     

A review on the research progress of push-out method in testing interfacial properties of SiC fiber-reinforced titanium matrix composites

Experimental analysis of single-fiber push-out for SiC fiber-reinforced titanium matrix composites (TMCs) is complicated by the incorporation of large thermal residual stresses, strong chemical bond of the fiber/matrix interface and matrix plastic deformation. This paper summarizes the development of push-out test and the characteristics of push-out test for TMCs such as crack initiating at the bottom face and theoretical analysis of the test. Moreover, it deeply analyzes the progresses of interfacial shear strength and fracture toughness, and work focus is pointed out in future.     

TEMPERATURE FIELD VISUALIZATION USING LIQUID CRYSTAL METHOD

The properties of liquid crystal thermoindicators were investigated in aerodynamic experiments. They are shown to be informative for visualization of the flow around the model and for subsonic and supersonic measurements of substantially inhomogeneous heat fluxes and the temperature fluxes on the model surfaces. The advantages and limitations of liquid crystal thermoindicators compared to other types of thermoindicators are analyzed.     

Determination of Copper and Aluminium in Steel by Means of Hollow Cathode and Glow Discharge Light Sources: A Comparative Study

Abstract

The applicability of hollow cathode and glow discharge light sources to the determination of minor constituents in steel was tested in the case of copper (0.033 ? 0.34[wt]%) and aluminium (0.015 ? 0. 16%). The linearity of the calibration graphs, reflected by the Bravais-Pearson coefficient, was found to be slightly improved in all the cases investigated when operating with hollow cathode. Furthermore, results showed that blackening values of the analytical lines can be plotted directly without resorting to reference lines.     

One‐Pot,Template‐Free Synthesis of Pd?Pt Single‐Crystalline Hollow Cubes with Enhanced Catalytic Activity

Hollow structures have attracted ever‐growing interest owing to their various excellent properties. However, a facile strategy for their fabrication is still desired. Herein, Pd? Pt alloy with three different morphologies, that is, cubes, hollow cubes, and truncated octahedrons, is synthesized by using a one‐pot, template‐free method. The mechanism and dynamics of this system is also studied in detail. In particular, the hollow cubic structure represents enhanced catalytic activity in both coupling reactions and in the electrochemical oxidation of formic acid.     

Synergistic Spectrophotometric and Atomic Absorption Spectrometric Analysis of Zinc in Alloys and Environmental Samples with N-p-MEthoxyphenyl-2-Furylacrylohydroxamic Acid and Pyridylazo Reagents

Abstract

Zinc (II) was selectively extracted from aqueous solutions of pH 7.8–8.5 into chloroform with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA). 1-(2-pyridylazo)-2-naphthol (PAN) or 2-[(5-nitro-2-pyridyl)azo]-1-naphthol (NPAN) were added to the extract to form intensely coloured ternary complexes measurable spectrophotometrically at 550 nm (? = 6.03 × 10⁴ 1 mol^?1 cm^?1) and 625 nm (? = 8.15 × 10⁴ mol^?1 cm^?1) respectively. For atomic absorption spectrometric analysis, methyl isobutyl ketone (MIBK) was used as extracting solvent instead of chloroform and the zinc-MFHA-MIBK extract was aspirated directly into an air-acetylene flame. The absorbance was measured at the 213.9 nm resonance line with a detection limit of 0.05 ppb, which was significantly better than the limit of 1.0 ppb achieved for zinc previously with flame AAS. The method tolerated a large number of anions and cations normally occurring with zinc in environmental samples, and was applied to the trace analysis of zinc in alloys, coal, plant tissues, animal tissues and natural waters. The combinations of MFHA and PAN/NPAN were chosen from eleven hydroxamic acids and nine pyridylazo reagents as detailed in the paper.