Mechanical property evaluation of an Al-2024 alloy subjected to HPT processing

An aluminum-copper alloy (Al-2024) was successfully subjected to high-pressure torsion (HPT) up to five turns at room temperature under an applied pressure of 6.0 GPa. The Al-2024 alloy is used as a fuselage structural material in the aerospace sector. Mechanical properties of the HPT-processed Al-2024 alloy were evaluated using the automated ball indentation technique. This test is based on multiple cycles of loading and unloading where a spherical indenter is used. After two and five turns of HPT, the Al-2024 alloy exhibited a UTS value of ~1014 MPa and ~1160 MPa respectively, at the edge of the samples. The microhardness was measured from edges to centers for all HPT samples. These results clearly demonstrate that processing by HPT gives a very significant increase in tensile properties and the microhardness values increase symmetrically from the centers to the edges. Following HPT, TEM examination of the five-turn HPT sample revealed the formation of high-angle grain boundaries and a large dislocation density with a reduced average grain size of ~80 nm. These results also demonstrate that high-pressure torsion is a processing tool for developing nanostructures in the Al-2024 alloy with enhanced mechanical propertie

Efecto de los parámetros del proceso sobre la estabilidad de la emulsión y el tamaño de la gota de aceite de granada en agua

The development of efficient emulsion is essential and requires a good understanding of the parameters that govern the formation and stability of the emulsion. The droplet size significantly affects the stability of the emulsion. In this study, the stability of pomegranate oil-in-water emulsions (0.5 to 7.0% v/v) was investigated using various emulsifiers in terms of droplet size and instability index during 16 days of storage. The Mastersizer and Lumisizer were used to measure the droplet size and instability index. It was observed that the minimum droplet size was achieved by using 0.3% carboxy methyl cellulose (5.37 μm) and maximum with 1.0/2.5% whey protein/maltodextrin (24.26 μm). The Lumisizer results during storage revealed the higher emulsion stability of carboxy methyl cellulose due to smaller droplet size and high thickness as compared to other emulsions studied. The findings of the present study would be useful for food applications to obtain fine and stable microcapsules.El desarrollo de una emulsión eficiente es esencial y requiere una buena comprensión de los parámetros que rigen la formación y la estabilidad de la emulsión. El tamaño de la gota afecta significativamente a la estabilidad de la emulsión. En este estudio, se investigó la estabilidad de las emulsiones de aceite de granada en agua (0,5 a 7,0% v/v) usando varios emulsionantes, en términos de tamaño de gota e índice de inestabilidad, durante 16 días de almacenamiento. El Mastersizer y el Lumisizer se usaron para medir el tamaño de gota y el índice de inestabilidad. Se observó que, el tamaño mínimo de gota se logró utilizando 0,3% de carboximetilcelulosa (5,37 μm) y el máximo (24,26 μm), con 1,0/2,5% de proteína de suero/maltodextrina Los resultados del Lumisizer, durante el almacenamiento, revelaron una mayor estabilidad de la emulsión de carboximetilcelulosa debido al tamaño de gota más pequeño y al alto espesor en comparación con otras emulsiones estudiadas. Los resultados del presente estudio se utilizarían en aplicaciones alimentarias para obtener microcápsulas finas y estables

Evaluating the Mechanical Properties of HPT Processed Aluminium Alloys Using Automated Ball-indentation Technique

AbstractAl-Cu and Al-Zn-Mg alloys exhibit excellent physical and mechanical properties, and are widely used for aerospace applications. However, these properties may be further improved through high-pressure torsion (HPT) processing. HPT processing was carried out on Al-2014 alloy and Al-7475 alloy to investigate the improvement in mechanical properties. Disks of coarse-grained Al- 2014 alloy and Al-7475 alloy were processed up to two turns of HPT, and the mechanical properties were evaluated using automated ball indentation (ABI) technique. HPT processing was carried out at atmospheric temperature, under pressure of 6GPa. The results show that, for Al-2014 alloy the ultimate tensile strength at the edge of HPT disk increased by a factor of ∼ 4, after 2 turns of HPT processing. Since, ABI technique provides the capability of obtaining extensive mechanical data using only a very small sample; it is an ideal procedure for evaluating the mechanical properties of samples processed by HPT

A comparison of repetitive corrugation and straightening and high-pressure torsion using an Al-Mg-Sc alloy

A comparative study was conducted to evaluate the influence of two different severe plastic deformation (SPD) processes: repetitive corrugation and straightening (RCS) and high-pressure torsion (HPT). Samples of an Al-3Mg-0.25Sc alloy with an initial grain size of ?150 ?m were processed by RCS through 8 passes at room temperature either without any rotation during processing or with a rotation of 90° around the longitudinal axis between each pass. Thin discs of the alloy were also processed for up to 5 turns by HPT at room temperature. The results show that both procedures introduce significant grain refinement with average grain sizes of ?0.6–0.7 ?m after RCS and ?95 nm after HPT. Measurements of the Vickers microhardness gave values of ?128 after RCS and ?156 after HPT. The results demonstrate that processing by HPT is the optimum processing technique in achieving both high strength and microstructural homogeneity