Excellent creep properties of Mg–Zn–Cu–Gd-based alloy strengthened by quasicrystals and Laves phases

2005 ◽  
Vol 20 (5) ◽  
pp. 1278-1286 ◽  
Author(s):  
Guangyin Yuan ◽  
Hidemi Kato ◽  
Kenji Amiya ◽  
Akihisa Inoue
Keyword(s):  
Mechanical Properties ◽  
Creep Condition ◽  
Strengthening Mechanism ◽  
Laves Phase ◽  
Az91 Alloy ◽  
Laves Phases ◽  
Creep Properties ◽  
Rare Earth Alloy ◽  
The Matrix ◽  
Icosahedral Quasicrystals

A new type of Mg–Zn–Cu–Gd-based alloy strengthened by quasicrystal and Laves phase was developed. This alloy exhibits much better creep properties compared to AE42(Mg–4 wt% Al–2 wt% rare-earth) alloy, which is the benchmark creep-resistant magnesium die-casting alloy under the compressive creep condition of 180 °C and80 MPa. The new alloy also exhibits high room-temperature mechanical properties close to that of AZ91 alloy. The good mechanical properties are attributed to the special microstructure; the thermally stable icosahedral quasicrystals phase (i-phase) and Laves phase distributed along the grain boundary as a hard skeleton, and some fine β′1 precipitates distributed homogenously on the matrix. The dislocation morphology after the creep test was studied, and the strengthening mechanism was proposed.

scholarly journals Assessing the Flexural Properties of Epoxy Composites with Extremely Low Addition of Cellulose Nanofiber Content

2020 ◽  
Vol 10 (3) ◽  
pp. 1159 ◽  
Author(s):  
Yingmei Xie ◽  
Hiroki Kurita ◽  
Ryugo Ishigami ◽  
Fumio Narita
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Flexural Modulus ◽  
Strengthening Mechanism ◽  
Short Fiber ◽  
Cellulose Nanofiber ◽  
Resin Matrix ◽  
Element Analysis ◽  
Epoxy Resin Matrix ◽  
The Matrix

Epoxy resins are a widely used common polymer due to their excellent mechanical properties. On the other hand, cellulose nanofiber (CNF) is one of the new generation of fibers, and recent test results show that CNF reinforced polymers have high mechanical properties. It has also been reported that an extremely low CNF addition increases the mechanical properties of the matrix resin. In this study, we prepared extremely-low CNF (~1 wt.%) reinforced epoxy resin matrix (epoxy-CNF) composites, and tried to understand the strengthening mechanism of the epoxy-CNF composite through the three-point flexural test, finite element analysis (FEA), and discussion based on organic chemistry. The flexural modulus and strength were significantly increased by the extremely low CNF addition (less than 0.2 wt.%), although the theories for short-fiber-reinforced composites cannot explain the strengthening mechanism of the epoxy-CNF composite. Hence, we propose the possibility that CNF behaves as an auxiliary agent to enhance the structure of the epoxy molecule, and not as a reinforcing fiber in the epoxy resin matrix.

Improvement of Mechanical Properties of Cu/Graphene Composite by In Site Reduction and Matrix Alloying with Titanium

2021 ◽  
Vol 1035 ◽  
pp. 925-930
Author(s):  
Ya Zhou Li ◽  
Yu Zhao ◽  
Xu Ran
Keyword(s):  
Mechanical Properties ◽  
Interface Design ◽  
Mass Fraction ◽  
Copper Substrate ◽  
Strengthening Mechanism ◽  
Copper Matrix ◽  
Carbide Formation ◽  
Plasma Sintering ◽  
Original Distribution ◽  
The Matrix

To reduce the agglomeration of graphene and enhance the interface bonding between reduced graphene oxide (RGO) and copper substrate, copper plating on the graphene surface was prepared by the in-situ reduction method. To improve the strength of the copper matrix, the microalloying strategy of adding titanium to the matrix was adopted. By changing the mass fraction of titanium in the matrix, the optimum ratio of RGO was obtained( Ti mass fraction was 5:1), and the tensile strength was maximized. The results show that RGO did not agglomerate obviously in the matrix. At the same time, the composite powder could be densified rapidly by spark plasma sintering (SPS), which could effectively protect the original distribution of the additive phase in the matrix. In this paper, Cu@RGO/Cu-Ti was prepared and the strengthening mechanism of the composites discussed, providing a new insights into the interface design and carbide formation mechanism of advanced graphene/copper composites with high mechanical properties.

scholarly journals Microstructure and mechanical properties of HR6W alloy dedicated for manufacturing of pressure elements in supercritical and ultrasupercritical power units

2019 ◽  
Vol 82 ◽  
pp. 01005 ◽  
Author(s):  
Grzegorz Golański ◽  
Agata Merda ◽  
Adam Zieliński ◽  
Paweł Urbańczyk ◽  
Jacek Słania ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Yield Strength ◽  
Base Alloy ◽  
Strength Properties ◽  
Laves Phase ◽  
Plastic Properties ◽  
The Matrix ◽  
Isothermal Ageing ◽  
Nickel Base

The article presents the results of research on the microstructure and selected mechanical properties of HR6W nickel-base alloy. The test alloy was subjected to isothermal ageing at 700°C and for up to 10000h. The tests of the HR6W microstructure were performed using the scanning electron microscopy (SEM) and the transmission electron microscopy (TEM). The performed microstructural tests of the HR6W alloy showed that in the as-received condition it was characterised by the structure of nickel austenite with numerous primary precipitates of NbC and TiN. Ageing of the investigated alloy contributed to the precipitation of numerous particles of varying morphologies inside the grains and at the grain boundaries, as well as at the boundaries of twins - they were the secondary precipitates of M23C6 and Laves phase. The number of the particles precipitated at the boundaries was so large that they formed the so-called continuous grid of precipitates. Inside the grains, the presence of compound complexes of precipitates was observed. These complexes consisted of the TiN particles, as well as the M23C6 carbides and Laves phase nucleating on them. The tests of the mechanical properties of HR6W alloy showed that in the as-received condition the alloy showed high plastic properties, with relatively low strength properties - in particular, the yield strength. Ageing of the HR6W alloy, as a result of precipitation of numerous particles in the matrix, through the strengthening with the precipitation mechanism, resulted in a considerable growth of the strength properties - inter alia the yield strength by over 60%, with the reduction of the plastic properties - elongation decreased by around 40%. Similar growth in the test alloy was observed for hardness.

scholarly journals Rheological Solidification Behavior and Mechanical Properties of AZ91-Sn Alloys

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 641 ◽  
Author(s):  
Di Tie ◽  
Boyu Zhang ◽  
Lufei Yan ◽  
Renguo Guan ◽  
Zhaoshan Ji ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Deformation ◽  
Eutectic Reaction ◽  
Az91 Alloy ◽  
Solidification Behavior ◽  
Magnesium Matrix ◽  
Solid Solution Strengthening ◽  
The Matrix ◽  
Deformation Behaviors ◽  
Solution Strengthening

The solidification and tensile deformation behaviors of rheo-cast AZ91-Sn alloys were revealed to study the effects of Sn alloying on improvement of AZ91 alloy’s mechanical properties. Two kinds of Mg17Al12 phases precipitated from the supersaturated magnesium matrix during rheo-solidification were observed: coarse discontinuous precipitates (DP) at grain boundaries and small-sized continuous precipitates (CP) inside grains. With increasing Sn content, the amount of Mg17Al12 phases was increased whilst the amount of Al atoms in the matrix was decreased. Due to the higher melting point of Mg2Sn than Mg17Al12, Mg2Sn precipitated earlier from the melt, and therefore provided heterogeneous nuclei for Mg17Al12 during the eutectic reaction. Due to grain refinement and solid solution strengthening, AZ91-2.4Sn (mass%) gained 52% increase in tensile strength and 93% increase in elongation compared with pure AZ91 alloy. The higher-density twins and microcracks induced by Sn alloying relaxed stress concentration during plastic deformation, so the fracture mode was transformed from cleavage fracture of pure AZ91 alloy to ductile fracture of AZ91-Sn alloys.

Effects of CeO2-Rich Mixed Rare Earth on the Mechanical Properties of Al2O3-Mullite Based Foam Ceramics

2010 ◽  
Vol 150-151 ◽  
pp. 815-820
Author(s):  
Shu Jun Ji ◽  
Xue Yi Guo ◽  
Jian Xiong Dong ◽  
Peng Su
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Rare Earth ◽  
Flexural Strength ◽  
Room Temperature ◽  
Strengthening Mechanism ◽  
Mechanism Analysis ◽  
Rare Earth Addition ◽  
The Matrix ◽  
Ceramic Microstructure

Using corundum, quartz, kaoline, etc, as base components and CeO2-rich mixed rare earth as modifier, foam ceramics were fabricated adopting the organic foam impregnation process. The mixed rare earth addition had much improving effects on the matrix mechanical properties owing to much glass phase and acerate mullite growing. While 3wt% was considered to be the optimal addition, in this case, homogeneous and compact ceramic microstructure with maximal glass condensation and minimal porosity formed, with the matrix compressive strength and the flexural strength at room temperature reached 0.87MPa and 0.66MPa respectively, which were 52.6% and 73.7% higher than the original samples respectively. As the mixed rare earth addition exceeded further, the compressive strength increased slowly and the flexural strength descended gradually. XRD and SEM were used to structure strengthening mechanism analysis.

A Study on Mechanical Properties and Strengthening Mechanisms of AA5052/ZrB2 In Situ Composites

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Narendra Kumar ◽  
Gaurav Gautam ◽  
Rakesh Kumar Gautam ◽  
Anita Mohan ◽  
Sunil Mohan
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Strengthening Mechanisms ◽  
In Situ Composites ◽  
Solid Solution Strengthening ◽  
Theoretical Yield ◽  
The Matrix

In the present study, in situ reaction technique has been employed to prepare AA5052 matrix composites reinforced with different vol. % of ZrB2 particles (i.e., 0, 4.5, and 9 vol. %). Composites have been characterized by X-ray diffraction (XRD) to confirm the in situ formation of ZrB2 particles in the matrix. Optical Microscopy (OM) studies reveal the refinement of aluminum-rich phase due to the presence of ZrB2 particles. Scanning electron microscopy (SEM) studies reveal size and distribution of ZrB2 particles while transmission electron microscopy (TEM) reveals the presence of dislocations in the matrix around ZrB2 particles. Hardness and tensile testing of composites have been carried out at room temperature to evaluate the mechanical properties. The results reveal the improvement in hardness and strength with increased amount of ZrB2 particles. Strength of AA5052/ZrB2 in situ composites has been analyzed by various strengthening mechanism models. The analysis revealed that Orowan and Solid solution strengthening mechanisms are the predominant mechanism for high strength composites. Theoretical yield strength is about 6–10% higher than the experimental values due to clustering tendency of ZrB2 particles.

Development of Magnesium Based Alloys for High Temperature Applications

2011 ◽  
Vol 673 ◽  
pp. 179-184 ◽  
Author(s):  
Uma Thanu Subramonia Pillai ◽  
Amirthalingam Srinivasan ◽  
Krishnamorthy Raghukandan ◽  
Ballembettu Chandrasekhar Pai
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Corrosion Behavior ◽  
Creep Resistance ◽  
Alloying Elements ◽  
Az91 Alloy ◽  
Thermally Stable ◽  
Creep Properties ◽  
Temperature Applications

Individual and combined additions of elements like Si, Sb, Sr are carried out to AZ91 alloy and its microstructure, mechanical properties especially creep properties and corrosion behavior are investigated. In general, additions of the above elements improve the mechanical properties. Further, the results show these alloying elements introduce thermally stable intermetallics and thereby improve the creep performance. Among various additions, Sb addition provides highest creep resistance. With the Si and Sr additions, the corrosion resistance of AZ91 alloy is improved. Detailed micro-mechanisms are also studied and they are correlated with the properties studied.

scholarly journals Tensile Mechanical Properties and Strengthening Mechanism of Hybrid Carbon Nanotube and Silicon Carbide Nanoparticle-Reinforced Magnesium Alloy Composites

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Xia Zhou ◽  
Depeng Su ◽  
Chengwei Wu ◽  
Liming Liu
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Magnesium Alloy ◽  
Room Temperature ◽  
Hybrid Composites ◽  
Coefficient Of Thermal Expansion ◽  
Strengthening Mechanism ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Sic Nanoparticles

AZ91 magnesium alloy hybrid composites reinforced with different hybrid ratios of carbon nanotubes (CNTs) and silicon carbide (SiC) nanoparticulates were fabricated by semisolid stirring assisted ultrasonic cavitation. The results showed that grains of the matrix in the AZ91/(CNT + SiC) composites were obviously refined after adding hybrid CNTs and SiC nanoparticles to the AZ91 alloy, and the room-temperature mechanical properties of AZ91/(CNT + SiC) hybrid composites were improved comparing with the unreinforced AZ91 matrix. In addition, the tensile mechanical properties of the AZ91 alloy-based hybrid composites were considerably improved at the mass hybrid ratio of 7 : 3 for CNTs and SiC nanoparticles; in particular, the tensile and yield strength were increased, respectively, by about 45 and 55% after gravity permanent mould casting. The reason for an increase in the room-temperature strength of the hybrid composites should be mainly attributable to the larger hybrid ratio of CNTs and SiC nanoparticles, the coefficient of thermal expansion (CTE) mismatch between matrix and hybrid reinforcements, the dispersive strengthening effects (Orowan strengthening), and the grain refining (Hall-Petch effect).

Influence of Cr2O3 Addition on the Properties of TiAl Composites

2011 ◽  
Vol 230-232 ◽  
pp. 789-792
Author(s):  
Jian Feng Zhu ◽  
Wen Wen Yang ◽  
Fang Ni Du
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Synthesis Method ◽  
Strengthening Mechanism ◽  
Reaction Synthesis ◽  
The Matrix ◽  
Method Effects ◽  
Particulate Reinforced

Using Ti, Al and Cr2O3 as starting materials, Al2O3 particulate reinforced TiAl composites have been fabricated by in-situ reaction synthesis method. Effects of the Cr2O3 addition on the microstructures and mechanical properties of the TiAl/Al2O3 composites were investigated in detail. The results show that the composites have a matrix of TiAl, Ti3Al, and minor Cr containing phases, and a second reinforcement Al2O3. The addition of Cr2O3 effectively refined the structure of the matrix, and as a result, the mechanical properties of TiAl composites are improved. At Cr2O3 7.36 wt%, the flexural strength and fracture toughness reach the maximum values of 634.62 MPa and 9.79 MPa·m1/2, which are increased by 80% and 30%, respectively. The strengthening mechanism is also discussed.

Study on Strengthening Mechanism of Cd Additions for AZ31 Magnesium Alloy

2010 ◽  
Vol 145 ◽  
pp. 293-297
Author(s):  
Shan Gao ◽  
Lan Ting Xia ◽  
Zhi Sheng Wu ◽  
Hong Zhan Li
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Impact Toughness ◽  
Brinell Hardness ◽  
Strengthening Mechanism ◽  
Az31 Magnesium Alloy ◽  
The Matrix ◽  
The Impact ◽  
New Phase ◽  
Tension Strength

The effect of Cd on the microstructure and mechanical properties of AZ31 magnesium alloy has been investigated in this paper. The results indicate that the microstructure of the AZ31 magnesium alloy is refined obviously by adding a little Cd. When 0.7%Cd is added, the alloy is made up of Al-rich α-Mg matrix and the phase of β-Mg17Al12 which distributes and disperses in the matrix uniformly. Cd solid dissolves in the matrix and there is no new phase formed, which contributes to the increase of the impact toughness, Brinell hardness, tension strength and elongation of the experimental alloy by 68.6%,10.3%,9% and 35%,respectively.

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