When a discontinuity in material properties exists across a bonded interface, stresses are generated as a result of any thermal or mechanical loading. These stresses significantly affect strength and failure characteristics and may be large enough to prevent successful fabrication of a reliable joint. The use of an interlayer material to successfully reduce mismatch stresses, thereby preventing joint failure or improving joint strength and reliability, requires knowledge of failure mechanisms and of the effects of interlayer properties on the critical stress components.The origin of residual stresses developed during cooling of a ceramic-metal joint from an elevated fabrication temperature is illustrated qualitatively in Figure 1. Away from edges, the in-plane (parallel to interface) stresses are typically compressive in the ceramic and tensile in the metal. These stresses can cause cracking perpendicular to the interface, leading to spalling or delamination failures. Such failures are frequently observed in thin-film and coating geometries. Where the interface intersects a free edge, large shear and axial (perpendicular to the interface) stresses are generated. The edge stresses are typically tensile within the ceramic and tend to promote crack propagation within the ceramic parallel and adjacent to the interface. This is the most commonly observed failure mode in bonded structural components.

This paper aims to establish the mechanical, corrosion and failure analysis using online acoustic emission of Al7075 alloy, Al7075-B 4 C composite and Al7075-B 4 C-Al 2 O 3 hybrid composite with different Boron Carbide (B 4 C) content of 5, 10, 15 & 20% and Nano Aluminium Oxide (Al 2 O 3 ) content of 2% on a weight basis with the high energy stir casting method. The casted samples have been characterized by x-ray Diffraction (XRD), Thermo gravimetric analysis (TGA/DSC), Energy Dispersive Spectrum (EDS), and Scanning Electron Microscope (SEM). In case of hybrid composite, the hardness and the tensile strength decrease when the content of Al 2 O 3 increases. However, in the present research, the addition of B 4 C with nano Al 2 O 3 particles in certain proportions has increased the hardness and tensile strength. In addition, the tensile fractographs of the specimens were analysed using SEM. Acoustic Emission (AE) method was used for monitoring the acoustic energy that are released at the time of deformation process and early crack detection. The influence of the volume fraction of the B 4 C particulates on the microstructural and corrosion characteristics of Al7075-B 4 C with nano Al 2 O 3 metal matrix composites (MMCs) was also studied. It has been observed from the literature that the direct strengthening of composites occurs due to the presence of hard ceramic phase, while the indirect strengthening arises from the thermal mismatch between the matrix alloy and reinforcing phase during solidification. Based on the database for material properties, the application area of HAMCs has been proposed in the present review. The effects of nanomaterial dispersion in the metal matrix and the formation of interfacial precipitates on these properties are also addressed. Particular attention is paid to the fundamentals and the structure-property relationships of such novel Nano composites.

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In India, urban solid waste generation has risen over the last decade. The aspect of waste generation is a large amount of waste materials among all solid waste types. While using ash particles eliminates waste, it also contributes desirable qualities. In this research work, the effects of Himalayan nettle leaf ash (HNLA) bean pod ash (BPA) with molybdenum trioxide (MoO3) on the ZWK611 (Mg-Zn6.0-Y1.2-Zr0.2) alloy is examined. The as-cast alloy exhibits an α-Mg matrix, and cubic γ-phases are formed in addition to MoO3 particles. In this work, an attempt was made to choose a ZWK611 alloy reinforced with HNLA and BPA by varying weight percentages (X = 4, 8, 12, and 15%) with a constant weight percentage of MoO3 (5%) fabricated using spark plasma sintering (SPS) technique. The mechanical and physical properties were tested for both as-cast alloy and magnesium hybrid composites. Surface morphology and XRD are analysed to identify material behaviour. The addition of 12%(HNLA-BPA)/5%(MoO3) hybrid composite exhibits high strength as compared to the as-cast alloy.

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