Fatigue Behavior of an Al-12.7Si-0.7Mg Alloy Processed by Extrusion and Heat Treatment

The fatigue life of a hot extruded Al-12.7Si-0.7Mg alloy under T1, T4, and T6 conditions was studied. The microstructure and tensile properties of the alloy were investigated in order to analyze the fatigue behavior. The results of the fatigue test showed that an extruded Al-12.7Si-0.7Mg alloy provided greater fatigue life compared to a cast Al-Si alloy, which was explained by the refined microstructure characterized by fine Si particles uniformly distributed in the Al matrix of fine equiaxed grains promoted by hot extrusion. The fatigue property of the alloy in T6 treatment was higher than that in the T4 and T1 conditions due to strengthening precipitation

Seismic analysis of fault damage zones in the northern Tarim Basin (NW China):Implications for growth of ultra-deep fractured reservoirs

Understanding fault damage zone is of significant importance for the characterization and modeling of ultra-deep (greater than 6000 m) fractured reservoirs. However, seismic detection of fracture networks in deep fault zone it is still challenging. For this contribution, we propose a seismic Tensor Thickness Method for optimal imaging of the ultra- strike-slip fault damage zones in the Tarim Basin. The results show reasonable distinction through seismic methods of boundary of fault damage zones in carbonate host rock that is consistent with the fractured reservoirs constrained from borehole data. In addition, this study suggests that fault damage zones in ultra deep settings exhibit width ranging 100–800 m, with a linear correlation between fault damage zone width and throw. Isolated fault zones are characterized with linear relationship between the width and displacement of the strike-slip fault zones, but the abnormally wide fault damage zone is likely attributed to fault interaction and overlapping. The results of this work are applicable for fractured reservoir characterization in deep and tight carbonate rocks elsewhere

Optimization of Inorganic Ceramic Membrane Filtration Process for Tea Enzymes

In order to enhance the clarity of tea enzymes while maximizing the preservation of their functional components during the clarification process, this experiment utilized tea enzymes derived from summer and autumn tea fermentation as the primary material. Through both single-factor and response surface experiments, the effects of inorganic ceramic membrane pore size, transmembrane power, transmembrane pressure, and transmembrane temperature on the content of functional components, membrane flux, transmittance, and soluble solids content of the enzyme solution after membrane filtration were examined. The objective was to determine the optimal conditions for ceramic membrane filtration of tea enzymes. The results showed that, the ideal conditions for ceramic membrane filtration of tea enzymes were as follows: Membrane pore size of 400 nm, transmembrane power of 47 Hz, transmembrane pressure of 0.28±0.02 MPa, and transmembrane temperature of 15±2 ℃. Under these conditions, the retention rates of tea polyphenols, theanine, zinc, selenium, and soluble solids content in tea enzymes were 95.28%, 82.91%, 90.48%, 91.67%, and 84.46% respectively. The transmittance reached 85.10%±0.12% with 2.5-fold improvement compared to before membrane filtration. Additionally, the membrane flux achieved 123.25±2.68 m3/(m2·h). These optimal conditions not only maximized the retention of functional components in tea enzymes, but also ensured their transparency and uniformity. Therefore, employing these conditions for the filtration and clarification of tea enzymes was a viable approach

Microstructural evolution of direct chill cast Al-15.5Si-4Cu-1Mg-1Ni-0.5Cr alloy during solution treatment

Heat treatment has important influence on the microstructure and mechanical properties of Al-Si alloys. The most common used heat treatment method for these alloys is solution treatment followed by age-hardening. This paper investigates the microstructural evolution of a direct chill (DC) cast Al-15.5Si-4Cu-1Mg-1Ni-0.5Cr alloy after solution treated at 500, 510, 520 and 530℃, respectively for different times. The major phases observed in the as-cast alloy are α-aluminum dendrite, primary Si particle, eutectic Si, Al7Cu4Ni, Al5Cu2Mg8Si6, Al15(Cr, Fe, Ni, Cu)4Si2 and Al2Cu. The Al2Cu phase dissolves completely after being solution treated for 2 h at 500℃, while the eutectic Si, Al5Cu2Mg8Si6 and Al15(Cr, Fe, Ni, Cu)4Si2 phases are insoluble. In addition, the Al7Cu4Ni phase is substituted by the Al3CuNi phase. The α-aluminum dendrite network disappears when the solution temperature is increased to 530℃. Incipient melting of the Al2Cu-rich eutectic mixture occurrs at 520℃, and melting of the Al5Cu2Mg8Si6 and Al3CuNi phases is observed at a solution temperature of 530℃. The void formation of the structure and deterioration of the mechanical properties are found in samples solution treated at 530℃

Aging Behavior and Precipitates Analysis of Wrought Al-Si-Mg Alloy

Aging behavior of wrought Al-12.7Si-0.7 Mg alloy was investigated during isothermal aging at 180 °C. Two aging peaks were observed at 3 h and 8 h, respectively. To examine precipitate evolution during aging, the alloy’s microstructure in different aging states was investigated by regular and high-resolution transmission electron microscopy (TEM and HRTEM). The results revealed that the variation of mechanical properties is attributed to the combining effect of Si particles, the grain boundary, and the character of precipitates. The predominant precipitates’ type, size, and volume fraction vary as aging time increases

Effect of hot extrusion process on microstructure and mechanical properties of hypereutectic Al-Si alloys

The hypereutectic Al-Si alloy was fabricated by hot extrusion process after solidified under electromagnetic stirring, and the microstructure and mechanical properties of the alloy were studied. The results show that the ultimate tensile strength and elongation of the alloy reached 229.5 MPa and 4.6%, respectively with the extrusion ratio of 10, and 263.2 MPa and 5.4%, respectively with extrusion ratio of 20. This indicates that the mechanical properties of the alloy are obviously improved with the increase of extrusion ratio. After hot extruded, the primary Si, eutectic Si, Mg2Si, AlNi, Al7Cu4Ni and Al-Si-Mn-Fe-Cr-Mo phases are refined to different extent, and the efficiency of refinement is obvious more and more with the increase of extrusion ratio. After T6 heat treatment, the sharp corners of these phases become passivated and roundish, and the mechanical properties are improved. The ultimate tensile strength of the extruded alloy after T6 heat treatment reaches 335.3 MPa with extrusion ratio of 10 and 353.6 MPa with extrusion ratio of 20

Distribution of lead in lead-containing aluminium alloys obtained by liquid phase co-spray forming technique

Liquid phase co-spray forming (LPCSF) technique was employed to produce AI-Pb and Al-Si-Pb alloys to show that it is possible, using this technique, to distribute lead into very fine-sized particles in Al/Al alloy matrix at low melt temperatures. Microstructural studies were carried out to explore the mechanisms governing lead distribution in the matrix of the alloys during processing. Results showed that, regardless of the alloy compositions and experimental conditions, the microstructures of the preforms exhibited great similarity, i.e. less uniform distribution of Pb particles in the base region, and uniform distribution of fine Pb particles in the equiaxed region. During LPCSF process, the behaviour of Pb droplets was similar to that of ceramic particles, except that the shape and size of liquid Pb phase varied corresponding to local solidification condition

Microstructure and mechanical properties of spray-formed Al-Si-Pb alloys

Liquid phase co-spray forming (LPCSF) was employed to produce two Al-Si-Pb alloys. The preforms thus obtained were then subjected to hot extrusion at different extrusion ratios. Following extrusion, the materials were tensile tested at room temperature. The distribution of Pb particles and the microstructural characterization in as-formed preforms and in the extruded rods were studied on the basis of SEM observation. The influence of the Pb content on the mechanical properties was investigated. (C) 2002 Published by Elsevier Science B.V

Microstructure and mechanical properties of Al-3Fe alloy processed by equal channel angular extrusion

International audienceAl-Fe alloys are attractive for applications at temperatures beyond those normally associated with the conventional aluminum alloys. Under proper solidification condition, a full eutectic microstructure can be generated in Al-Fe alloys at Fe concentration well in excess of the eutectic composition of 1.8 wt.% Fe. The microstructure in this case is characterized by the metastable regular eutectic Al-Al6Fe fibers of nano-scale in diameter, instead of the equilibrium eutectic Al-Al3Fe phase. In this study, the microstructure and mechanical properties of the Al-3Fe alloy with metastable Al6Fe particles deformed by equal channel angular extrusion were investigated. Severe plastic deformation results in a microstructure consisting of submicron equiaxed Al grains with a uniform distribution of submicron Al6Fe particles on the grain boundaries. The room temperature tensile properties of the alloy with this microstructure will be presented

Fundamental differences between spray forming and other semisolid processes

The distinguished microstructural features of spray formed products are the refined equiaxed grain structure and lower segregation level. Attempts have been made in the past to propose mechanisms to explain the formation of equiaxed grain structure. Recently there has been a tendency in correlating spray forming with other semisolid processes such as liquid phase sintering (LPS) and rheocasting. In this article, the fundamental differences between spray forming and the other semisolid processes are discussed. Results show a unique thermal and solute profile on the deposit surface, resulting from the mixing of rapidly solidified metal formed during atomization and the solute-poor liquid formed by addition of the liquid of alloy composition, which contributes mainly to the microstructural evolution during spray forming. A simple experiment was designed to give supporting evidence to this view