scholarly journals The influence of iron impurities on the compression behaviour of Al-2.24Mg-2.09Li alloy

2020 ◽  
pp. 38-38
Author(s):  
Franjo Kozina ◽  
Zdenka Zovko-Brodarac ◽  
Mitja Petric ◽  
Andrej Penko
Keyword(s):  
Grain Boundaries ◽  
Strength Properties ◽  
Solution Hardening ◽  
Microstructural Investigation ◽  
Microstructure Changes ◽  
Compression Behaviour ◽  
Intermetallic Particles ◽  
Cast Condition ◽  
Al Matrix ◽  
Hardened Condition

As a major impurity element in aluminium-lithium (Al-Li) alloys, iron (Fe) reduces formability, fracture toughness and fatigue resistance by solidifying into Al6Fe and Al3Fe particles. The research was performed in order to estimate the influence of Fe impurities on the compression behaviour of Al-2.24Mg-2.09Li alloy. The investigation was performed on the samples in as cast and solution hardened condition. The solution hardening was applied to improve the mechanical properties by dissolving intermetallic particles and enriching ?Al matrix with Mg. However, the higher strength properties and temperature increase during the compression testing were observed in as cast condition. Microstructural investigation revealed significant differences in microstructure changes between the samples in as cast and solution hardened condition. In as cast sample the barrelling effect led to the unequal deformation and surface texture development. The eutectic Al3Fe particles located in the ?Al interdendritic areas did not significantly impact microstructure changes. Even due the solution hardening led to enrichment of ?Al matrix with Mg and Fe, the Al3Fe particles were not dissolved. The coarse morphology of Al3Fe particles and location at the grain boundaries of ?Al grains contributed to low energy intergranular fracture. The fracture nucleation and propagation across the grain boundaries resulted in lower strength values.

Effects of Ca and RE Additions on the Precipitation and Microstructure of As-Cast AZ91 Alloy

2017 ◽  
Vol 865 ◽  
pp. 30-35 ◽  
Author(s):  
Li Fu ◽  
Qi Chi Le ◽  
Pei Li Gou ◽  
Xi Bo Wang ◽  
Xuan Liu
Keyword(s):  
Intermetallic Compound ◽  
Grain Boundaries ◽  
Intermetallic Compounds ◽  
Lamellar Structure ◽  
Az91 Alloy ◽  
Sem Images ◽  
Xrd Pattern ◽  
Microstructure Changes ◽  
Polygonal Structure ◽  
Cast Alloys

The effect of Ca and RE metal additions on the precipitation and microstructure of as-cast AZ91 alloy was systematically investigated. It was found that Ca and RE additions could result in phase and microstructure changes. The XRD pattern showed the crystallite phase of as-cast AZ91 alloys consists of α-Mg matrix and β-Mg17Al12, however, after adding 1.5wt. % Ca and 0.8wt. % RE (0.5wt. % Sm and 0.3wt. % La), peaks coincident with Al2Ca, Al2Sm and Al11La3 intermetallic compounds were found, suggesting the generation of relative precipitates. The SEM images indicated that in as-cast alloys, the Al2Ca intermetallic compound was located at grain boundaries with a lamellar structure, and the Al2Sm intermetallic compound was homogeneously distributed in the α-Mg matrix or near the grain boundaries with a polygonal structure, and the Al11La3 intermetallic compound was located at grain boundaries with a needlelike structure. These intermetallic compounds could reduce the amount of β-Mg17Al12 and refine the microstructure of as-cast AZ91 alloy.

scholarly journals Structural and Mechanical Properties of Amorphous Si3N4 Nanoparticles Reinforced Al Matrix Composites Prepared by Microwave Sintering

Ceramics ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 126-134 ◽  
Author(s):  
Manohar Mattli ◽  
Penchal Matli ◽  
Abdul Shakoor ◽  
Adel Amer Mohamed
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Yield Strength ◽  
Volume Fraction ◽  
Microwave Sintering ◽  
Aluminum Matrix ◽  
Microstructural Investigation ◽  
Porosity Level ◽  
Amorphous Si3n4 ◽  
Al Matrix

The present study focuses on the synthesis and characterization of amorphous silicon nitride (Si3N4) reinforced aluminum matrix nanocomposites through the microwave sintering process. The effect of Si3N4 (0, 1, 2 and 3 wt.%) nanoparticles addition to the microstructure and mechanical properties of the Al-Si3N4 nanocomposites were investigated. The density of Al-Si3N4 nanocomposites increased with increased Si3N4 content, while porosity decreased. X-ray diffraction (XRD) analysis reveals the presence of Si3N4 nanoparticles in Al matrix. Microstructural investigation of the nanocomposites shows the uniform distribution of Si3N4 nanoparticles in the aluminum matrix. Mechanical properties of the composites were found to increase with an increasing volume fraction of amorphous Si3N4 reinforcement particles. Al-Si3N4 nanocomposites exhibits higher hardness, yield strength and enhanced compressive performance than the pure Al matrix. A maximum increase of approximately 72% and 37% in ultimate compressive strength and 0.2% yield strength are achieved. Among the synthesized nanocomposites, Al-3wt.% Si3N4 nanocomposites displayed the maximum hardness (77 ± 2 Hv) and compressive strength (364 ± 2 MPa) with minimum porosity level of 1.1%.

Architectured Multi-Metallic Structures Prepared by Cold Dynamic Spray Deposition

2019 ◽  
Vol 810 ◽  
pp. 107-112
Author(s):  
Ivo Dlouhý ◽  
Lukas Rehorek ◽  
Hanuš Seiner ◽  
Jan Čížek ◽  
Filip Šiška
Keyword(s):  
Spray Deposition ◽  
Strength Properties ◽  
Metallic Materials ◽  
Metallic Structures ◽  
Ti Alloys ◽  
Spatial Ordering ◽  
Beam Patterns ◽  
Theoretical Considerations ◽  
Single Material ◽  
Al Matrix

The architectured metallic materials are a class of composite materials that combines two or more metals/alloys with a specific spatial ordering (architecture). The main goal behind the preparation of such materials is to obtain properties that are not achievable by a single material. The internal architecture thus creates an extra degree of freedom in materials design. Based on theoretical considerations three aluminum alloy structures containing square, triangle and sinusoidal iron beam patterns have been prepared by a cold spray deposition technique. Strength properties difference and good bonding of the reinforcing Fe structure to the Al matrix has been found to be important for effective improvement of final properties. Incorporating about 30 vol. % structured iron beams into the Al matrix resulted in a macroscopic performance of the architectured multimaterial similar to Ti alloys.

Microstructure and mechanical properties of Fe–Al–Nb–B alloys

MRS Advances ◽  
2017 ◽  
Vol 2 (25) ◽  
pp. 1353-1359 ◽  
Author(s):  
Shahbaz Ahmed Azmi ◽  
Alena Michalcová ◽  
Lucia Senčekova ◽  
Martin Palm
Keyword(s):  
Mechanical Properties ◽  
Ternary System ◽  
Grain Boundaries ◽  
Laves Phase ◽  
Uneven Distribution ◽  
Strengthening Effect ◽  
Heusler Phase ◽  
Microstructure And Mechanical Properties ◽  
Al Matrix

ABSTRACTDoping of Fe–Al–Nb alloys with boron results in precipitation of stable C14 Laves phase Nb(Fe,Al)2 instead of metastable Heusler phase Fe2AlNb as in case of the ternary system. The boron stimulated precipitation of the Laves phase leads to preferential precipitation of the Laves phase along grain boundaries and – with higher supersaturation of Nb in the Fe-Al matrix – to an even distribution of additional precipitates within the grains. Though these microstructures seem to be more favourable than in the boron-free alloys, which show an uneven distribution of rather large Laves phase precipitates, no marked strengthening effect by the Laves phase in the Fe–Al–Nb–B alloys is observed.

Research of reinforcement phase formation on the borders of sintered berillium grains

2020 ◽  
pp. 25-33
Author(s):  
A. V. Revutsky ◽  
V. Yu. Syrnev ◽  
V. Yu. Lopatin ◽  
O. V. Semilutskaya ◽  
T. A. Segeda
Keyword(s):  
Mechanical Properties ◽  
Grain Boundaries ◽  
High Strength ◽  
Beryllium Oxide ◽  
Research Problem ◽  
Strength Properties ◽  
Reinforcing Particles ◽  
Morphology And Structure ◽  
The Difference ◽  
Devitrification Mechanism

The paper presents the results of studying the effect of the state of grain boundaries (formed in the consolidation of beryllium powders by vacuum hot pressing on the strength properties of sintered beryllium. Scanning electron microscopy and X-ray spectral microanalysis were used to study the dependences of the morphology, elemental composition and structure of a dispersion hardening phase - beryllium oxide – on the content of low-melting impurities at the grain boundaries of sintered beryllium. A new hypothesis is proposed to explain the difference in the morphology and structure of reinforcing particles based on the transition features of amorphous beryllium oxide to a crystalline state (devitrification) at the grain boundaries of metallic beryllium. It is theoretically substantiated and experimentally confirmed that the devitrification mechanism can be homogeneous or heterogeneous depending on the content and ratio of silicon and aluminum impurities. This difference leads to the formation of either finely dispersed high-strength reinforcing particles of beryllium oxide or large, lower-strength oxide clusters. Changes in the morphology and structure of reinforcing oxide particles at the metallic beryllium grain boundaries, in its turn, influence the dynamics of beryllium microstructure grain growth during vacuum hot forming and, ultimately, the effect of dispersed grain-boundary hardening of sintered n beryllium. The paper provides the statistically processed results of testing the mechanical properties of industrial hot-pressed blanks produced of less than 56 μm powders to determine the effect of various factors (the content of impurities, their ratio and particle size of the initial powders) on the strength properties of hot-pressed beryllium. The adequacy of the obtained regularities was evaluated using the approximation confidence coefficients and confirmed the conclusions made in the theoretical and experimental analysis of the research problem. The statistical studies substantiated a comprehensive quality indicator of initial powders in order to predict the strength properties of hot-pressed beryllium. The results obtained substantiate new possibilities for controlling the mechanical properties of sintered beryllium for various purposes.

Annealing Characteristics of Al-Light-Rare-Earth Alloy Thin Films for Microelectronic Conductor Lines

1995 ◽  
Vol 403 ◽  
Author(s):  
Shinji Takayama ◽  
Naganori Tsutsui
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Rare Earth ◽  
Grain Boundaries ◽  
High Temperatures ◽  
Light Rare Earth ◽  
Rare Earth Alloy ◽  
Metallic Compounds ◽  
Al Matrix

AbstractThe addition of La and Pr to Al thin films markedly decreases the grain size of the Al matrix and largely suppresses growth of thermal defects of hillocks and whiskers at high temperatures (350°C – 450°C). A large number of fine metallic compounds of Al11RE3 and/or Al3RE (RE = La and Pr) were segregated in an Al matrix, mostly at grain boundaries, after annealing at 350°C. The resistivities of the films after annealing at the above temperatures show very low values of less than 6 μωcm, without the salient formation of hillocks or whiskers on the film surfaces.

DSC and Microstructural Investigations of the Elektron 21 Magnesium Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 1447-1452 ◽  
Author(s):  
Andrzej Kiełbus ◽  
Tomasz Rzychoń ◽  
Roman Przeliorz
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Magnesium Alloy ◽  
Solution Heat Treatment ◽  
Casting Alloy ◽  
Solution Hardening ◽  
Ageing Treatment ◽  
Aerospace Application ◽  
Different Temperatures ◽  
Cast Condition

The paper presents the results of DSC and microstructural investigations of Elektron 21 magnesium alloy in as cast condition and after solution hardening. Elektron 21 is a magnesium based casting alloy containing neodymium and gadolinium for used to at 200°C in aerospace application. The solution heat treatment was performed at 520°C/8h/water. Ageing treatment was performed at different temperatures 200, 250, 300 and 350°C, then quenched in air. The microstructure of Elektron 21 in as cast condition consists of primary solid solution α -Mg grains with eutectic α-Mg + Mg3(Nd,Gd) phase and regular precipitates of MgGd3 phase. After DSC investigations three exothermal signals has been observed. First exothermal signal at ~170÷245°C assigned to an undifferentiated formation of the metastable phases β” and β’ and the second one at ~280°C corresponded to the formation of a stable β (Mg3Nd) phase. The last signal at ~300°C was connected to the formation of Mg41Nd5 phase. Regular precipitates of MgGd3 phase have been also observed. TEM investigation confirmed that the Elektron 21 alloy precipitate from the solid solution according to the sequence of the following phases: α–Mgβ”β’β(Mg3Nd)Mg41Nd5

Influence of Boron on the Micro-Organization Mechanism of Zirconium Containing Aluminium Alloy

2011 ◽  
Vol 284-286 ◽  
pp. 1506-1509
Author(s):  
Sheng Yang ◽  
Peng San
Keyword(s):  
Phase Composition ◽  
Grain Boundaries ◽  
Aluminium Alloy ◽  
Lattice Distortion ◽  
Second Phase ◽  
Influence Mechanism ◽  
Al Matrix ◽  
Organization Mechanism

In this paper, the influence of B on the existence form and the phase composition of Zr in alloy were studied. And the influence mechanism of B on Zr in alloy was analyzed. The results show that the addition of B makes part of Zr become precipitation present in grains and grain boundaries as the small plate sheet of second phase from solution. It reduced the lattice distortion, improved the ordering of Al matrix and the conductivity of the alloy.

Fabrication of Al-Based Matrix Composite Reinforced with WAl12 Intermetallic Particles by Press-Forming Process Using High-Energy Ball-Milled Powders

2012 ◽  
Vol 476-478 ◽  
pp. 574-578
Author(s):  
Shu Guang Cai
Keyword(s):  
Composite Material ◽  
Matrix Composite ◽  
High Energy ◽  
Forming Process ◽  
Forming Technology ◽  
Press Forming ◽  
Intermetallic Particles ◽  
Energy Ball ◽  
Al Matrix ◽  
Milled Powders

The 22wt%WAl12intermetallic particulate reinforced Al-based matrix composite was successfully fabricated by press-forming technology using high-energy ball-milled powders. X-ray diffraction analysis shows that WAl12reinforcement phase has been obtained after in situ reaction of Al matrix with W14Al86alloy at 620°C. The mechanical properties of the composite material were studied at room temperature. The Young’s modulus, microhardness and the maximum ultimate tensile strength of this composite material can reach 75GPa, 1.51GPa and 471MPa, respectively. The results show that there is a good interfacial bonding between the Al matrix and WAl12particles. However, the composite cannot be applied in high temperature environment because of its fairly low strength residual ratio.

The Effect of Boron Addition on Precipitation and Hot Ductility of 1.5Mn-0.1Nb-Ti Carbon Steels in As-Cast Condition

2016 ◽  
Vol 879 ◽  
pp. 990-995 ◽  
Author(s):  
Jacek Komenda ◽  
David Martin ◽  
Johan Lönnqvist
Keyword(s):  
Grain Boundaries ◽  
Base Composition ◽  
Prior Austenite ◽  
Carbon Steels ◽  
Hot Ductility ◽  
Austenite Grain ◽  
Reduction In Area ◽  
Cast Condition ◽  
Prior Austenite Grain ◽  
Start Temperature

Twelve experimental steels with a base composition 1.5wt% Mn, 0.01 wt% V and 0.1 wt% Nb and varying C (0.05, 010 and 0.20 wt%), Ti (20 – 260 ppm) and B (0 – 100 ppm) contents have been systematically examined to quantify the effects of composition on precipitation behavio-ur and hot ductility during simulated continuous casting conditions. Nb-rich precipitates were present in the alloys with 0.10 wt-% C and 0.20 wt-% C. Alloys with 0.05, 010 and 0.20wt% C contained 50 – 100 nm size Ti-Nb carbonitrides. Boron was bound in 20 – 100 nm size boronitrides located in prior austenite grain boundaries. A Gleeble 3800 was used to study hot ductility and strain induced precipitation processes in the alloys. Alloys without B and Ti additions exhibited poor hot ductility at 850°C and 950°C, whereas the 0.05 wt-% C and 0.10 wt-% C alloys showed improved hot ductility (reduction in area 40-50%) by the addition of either >50 ppm B or 250 ppm Ti. The 0.2 wt-% C alloys showed no improvement from B or Ti additions. Examination of fracture surfaces of hot ductility specimens showed that boronitrides were located at prior austenite grain boundaries in alloys containing 80 – 100 ppm of B. Compression-relaxation tests showed that alloying with boron caused a noticeable decrease of the start temperature of strain-induced precipitation in the alloys.

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