A Method for the Production of Large Sized Al-B4C-Al2O3np Nanocomposites through Liquid-State Process

2017 ◽  
Vol 753 ◽  
pp. 84-92
Author(s):  
Wei Liu ◽  
Qiu Lin Li ◽  
Wei Liu ◽  
Guo Gang Shu ◽  
Qi Sun ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Ball Milling ◽  
Liquid State ◽  
Room Temperature ◽  
Milling Time ◽  
Mixed Powder ◽  
State Process ◽  
Semi Solid

The paper introduces a new method to produce large sized Al-B4C-Al2O3np composites, which combines ball milling to prepare Al2O3np/Al mixed powder and semi-solid casting to contribute the injection of Al2O3np/Al mixed powder into the melt. The deformation performance of Al2O3np and micro-Al through ball milling with different Al/Al2O3np ratios, different milling time and different balls were studied respectively. It was revealed that micro-Al particles were milled from twisted and crimpled foil pieces to shuttles with Al2O3np embedded on it through 4h milling with 10mm balls. And we consider it as the best bonding between Al2O3np and micro-Al we could attain. And a plate of 25kg of Al-B4C-Al2O3np composite was fabricated successfully with the injection of the Al2O3np/Al mixed powder. Spherical Al2O3np of 300nm and needle-like TiB2 with 200nm in radius and 800nm-4μm in length were found in SEM photographs. Tensile properties of Al-B4C-Al2O3np composites were tested at room temperature and high temperature. It was showed higher mechanical properties than Al-B4C composites at room temperature and elevated temperature. Particularly, a 40% increase of UTS of Al-15wt.% B4C-1wt.%Al2O3np at 350°C was observed.

Deformation of an extruded nickel beryllide between room temperature and 820 °C

1991 ◽  
Vol 6 (12) ◽  
pp. 2653-2659 ◽  
Author(s):  
G.M. Pharr ◽  
S.V. Courington ◽  
J. Wadsworth ◽  
T.G. Nieh
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Flow Stress ◽  
Strain Hardening ◽  
Room Temperature ◽  
High Temperature Strength ◽  
Compression Tests ◽  
Tension And Compression ◽  
Better Than

The mechanical properties of nickel beryllide, NiBe, have been investigated in the temperature range 20–820 °C. The room temperature properties were studied using tension, bending, and compression tests, while the elevated temperature properties were characterized in compression only. NiBe exhibits some ductility at room temperature; the strains to failure in tension and compression are 1.3% and 13%, respectively. Fracture is controlled primarily by the cohesive strength of grain boundaries. At high temperatures, NiBe is readily deformable—strains in excess of 30% can be achieved at temperatures as low as 400 °C. Strain hardening rates are high, and the flow stress decreases monotonically with temperature. The high temperature strength of NiBe is as good or better than that of NiAl, but not quite as good as CoAl.

scholarly journals Determination of Quantity and Localization of Liquid in the Semi-Solid State Using both 3D X-Ray Microtomography and 2D Techniques for Steel Thixoforming

2012 ◽  
Vol 192-193 ◽  
pp. 191-196
Author(s):  
Guo Chao Gu ◽  
Raphaël Pesci ◽  
Eric Becker ◽  
Laurent Langlois ◽  
Régis Bigot
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Solid State ◽  
Room Temperature ◽  
Great Influence ◽  
Ex Situ ◽  
X Ray ◽  
Semi Solid

The distribution of liquid at the semi solid state is one of the most important parameters for steel thixoforging. It has a great influence on the viscosity of the material, on the flows and finally on the final shape and mechanical properties of the thixoforged parts. Both ex situ and in situ 3D X-ray microtomography characterizations have been carried out to determine the quantity and localization of liquid at high temperature of M2 steel slugs. Microtomography was first performed ex situ at room temperature on samples heated and quenched from semi-solid state. The specimens were also scanned in situ directly at high temperature. The obtained results have been compared to 2D observations using EDS technique in SEM on heated and quenched specimens. They showed a good correlation making both approaches very efficient for the study of the liquid zones at the semi-solid state

scholarly journals Microstructures and High-Temperature Properties of Sm-Modified Mg-4Al-4RE Alloy

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 135
Author(s):  
Hongkui Mao ◽  
Xiaoyu Bai ◽  
Yu Wang ◽  
Hong Xu ◽  
Jibo Hou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Tensile Stress ◽  
Tensile Properties ◽  
Yield Stress ◽  
Room Temperature ◽  
Volume Fraction ◽  
Ultimate Tensile Stress ◽  
New Phase

The effect of Sm on the microstructure and tensile properties of Mg-4Al-4 (La, Ce) alloy was studied. The Mg-4Al-4 (La, Ce) alloy was mainly composed of α-Mg and Al11(La, Ce)3. With the addition of Sm, a new phase of Al2(La, Ce, Sm) was revealed in the alloy. The results showed that at room temperature (RT), after Sm addition, the ultimate tensile stress and the elongation decreased, while the yield stress increased slightly; the elongation increased with the Sm addition and the yield stress was basically the same, but the ultimate tensile stress decreased at an elevated temperature of 150 °C. The change in the mechanical properties of the alloy was mainly related to the change in microstructure and phase. With the increase in Sm content, the volume fraction of Al2(La, Ce, Sm) phase increased and the Al11(La, Ce)3 eutectic volume fraction decreased significantly, which led to a change in the mechanical properties of the alloy. The 1 wt.%Sm-addition alloy exhibited greater elongation than the Sm-free alloys.

The Mechanical Properties and Thermal Resistance of Fly Ash Geopolymer Foams

2018 ◽  
Vol 281 ◽  
pp. 175-181
Author(s):  
Hui Teng Ng ◽  
Cheng Yong Heah ◽  
Yun Ming Liew ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Kamarudin Hussin
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Peroxide ◽  
Compressive Strength ◽  
High Temperature ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Thermal Resistance ◽  
Bulk Density ◽  
Room Temperature ◽  
Heating Up

In the present work, a comparative study of the thermal performance of unfoamed and foamed geopolymers was investigated. The geopolymers were prepared by mixing fly ash with alkali activator (a mixture of sodium hydroxide and sodium silicate). The geopolymer foams were prepared by adding hydrogen peroxide (H2O2, 2wt.% and 4wt.%). The geopolymers were cured at room temperature (29°C) for 24 hours and at 60°C for another 24 hours. The bulk density and compressive strength decreased with increasing H2O2 up to 2wt.% and increased when 4wt.% of H2O2 was added. In order to test the thermal resistance, the geopolymers were heated at elevated temperature (200- 1000°C). Unheated geopolymers showed bulk density and compressive strength in the range of 1.6– 1.7g/cm3 and 15–17MPa, respectively. When heated up to 1000°C, the geopolymers could withstand high temperature without any disintegration and spalling. Both unfoamed and foamed geopolymers showed highest compressive strength at 200°C (17–22MPa). Further decreased in compressive strength was observed upon heating up to 800°C (10–17MPa). The compressive strength regained (14–21MPa) when heated up to 1000°C. The compressive strength was even higher than that recorded at room temperature. In the present work, unfoamed geopolymers showed overall higher thermal resistance than foamed geopolymers.

Experimental Investigation and Micro-Structural Evolution Analysis of CNT & Fly Ash Reinforced Aluminium Matrix Composites

2015 ◽  
Vol 830-831 ◽  
pp. 429-432 ◽  
Author(s):  
Udaya ◽  
Peter Fernandes
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Fly Ash ◽  
Ball Milling ◽  
Milling Time ◽  
Structural Evolution ◽  
Matrix Composites ◽  
Evolution Analysis ◽  
Ball Milling Time ◽  
Al Matrix

The paper illustrates Carbon nanotubes reinforced pure Al (CNT/Al) composites and fly ash reinforced pure Al (FA/Al) composites produced by ball-milling and sintering. Microstructures of the fabricated composite were examined and the mechanical properties of the composites were tested and analysed. It was indicated that the CNTs and fly ash were uniformly dispersed into the Al matrix as ball-milling time increased with increase in hardness.

scholarly journals Characterization and Comparison of Geopolymer Synthesized Using Metakaolin Bangka and Metastar as Precursors

2018 ◽  
Vol 67 ◽  
pp. 03022
Author(s):  
Sotya Astutiningsih ◽  
Dicky Tambun ◽  
Ahmad Zakiyuddin
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Mechanical Test ◽  
Strength Test ◽  
Thermal Activity ◽  
Metallurgical Properties ◽  
Metakaolin Geopolymer ◽  
Kaolin Deposit

Various aluminosilicate material have been used as precursor for geopolymer. Geopolymer gets its strength from the polycondensation of silicate and alumina. Metakaolin, calcinated kaolin, is pozzolan with the highest alumina and silicate purity. Indonesia, especially Bangka Island, has a large amount of kaolin deposit that being sold at low price. This price could be increased ten times when being sold as metakaolin. This study aimed to compare mechanical and metallurgical properties of commercial metakaolin and Bangka kaolin which calcinated at 700°C. Both metakaolins reacted with NaOH and waterglass as the activator followed by curing at room temperature for 7, 14 and 28 days and elevated temperature of 60°C for 4, 12 and 24 hours. Mechanical properties will be examined by compressive strength and flexural strength test, while the metallurgical properties will be evaluated with SEM, and TAM. The results of the mechanical test will be used to determine which geopolymer will perform well with the microstructure and thermal activity to support the finding. These attempts will be done in order to improve the properties of Bangka metakaolin geopolymer superior to commercial metakaolin.

Effect of High Temperature on Concrete: A Literature Review

2006 ◽  
Vol 302-303 ◽  
pp. 138-149 ◽  
Author(s):  
Gai Fei Peng ◽  
Sammy Yin Nin Chan ◽  
Qi Ming Song ◽  
Quan Xin Yi
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Literature Review ◽  
High Strength Concrete ◽  
High Strength ◽  
Research Needs ◽  
Standard Fire ◽  
Fire Condition

This paper presents a review on the effect of fire on concrete, citing 43 references. It was found that most of them are on the behavior of concrete under high temperature conditions more or less different from the standard fire condition. The problem of spalling, which high-strength concrete encounters when exposed to fire, is especially urgent to solve. Since the literature on the behavior of concrete under fire conditions is very limited, the literature even under elevated temperature has to be used as a part of the base of further research. The further research needs urgently to be carried out under the standard fire condition. Residual mechanical properties reported in most previous literature might be overestimated, where natural cooling was usually employed. Proper evaluation of fire resistance of concrete needs more experimental data obtained under various cooling regimes such as water spraying or water quenching.

scholarly journals Comparison of Mechanical and Microstructural Properties of as-Cast Al-Cu-Mg-Ag Alloys: Room Temperature vs. High Temperature

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1330
Author(s):  
Muhammad Farzik Ijaz ◽  
Mahmoud S. Soliman ◽  
Ahmed S. Alasmari ◽  
Adel T. Abbas ◽  
Faraz Hussain Hashmi
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Mechanical Testing ◽  
Tensile Testing ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Microstructural Properties ◽  
Testing Environments ◽  
Mechanical And Microstructural Properties ◽  
Mg Content

Unfolding the structure–property linkages between the mechanical performance and microstructural characteristics could be an attractive pathway to develop new single- and polycrystalline Al-based alloys to achieve ambitious high strength and fuel economy goals. A lot of polycrystalline as-cast Al-Cu-Mg-Ag alloy systems fabricated by conventional casting techniques have been reported to date. However, no one has reported a comparison of mechanical and microstructural properties that simultaneously incorporates the effects of both alloy chemistry and mechanical testing environments for the as-cast Al-Cu-Mg-Ag alloy systems. This preliminary prospective paper presents the examined experimental results of two alloys (denoted Alloy 1 and Alloy 2), with constant Cu content of ~3 wt.%, Cu/Mg ratios of 12.60 and 6.30, and a constant Ag of 0.65 wt.%, and correlates the synergistic comparison of mechanical properties at room and elevated temperatures. According to experimental results, the effect of the precipitation state and the mechanical properties showed strong dependence on the composition and testing environments for peak-aged, heat-treated specimens. In the room-temperature mechanical testing scenario, the higher Cu/Mg ratio alloy with Mg content of 0.23 wt.% (Alloy 1) possessed higher ultimate tensile strength when compared to the low Cu/Mg ratio with Mg content of 0.47 wt.% (Alloy 2). From phase constitution analysis, it is inferred that the increase in strength for Alloy 1 under room-temperature tensile testing is mainly ascribable to the small grain size and fine and uniform distribution of θ precipitates, which provided a barrier to slip by deaccelerating the dislocation movement in the room-temperature environment. Meanwhile, Alloy 2 showed significantly less degradation of mechanical strength under high-temperature tensile testing. Indeed, in most cases, low Cu/Mg ratios had a strong influence on the copious precipitation of thermally stable omega phase, which is known to be a major strengthening phase at elevated temperatures in the Al-Cu-Mg-Ag alloying system. Consequently, it is rationally suggested that in the high-temperature testing scenario, the improvement in mechanical and/or thermal stability in the case of the Alloy 2 specimen was mainly due to its compositional design.

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