Phase Transformations in the Zirconium-Aluminum-Hydrogen System

1975 ◽  
Vol 33 ◽  
pp. 28-29
Author(s):  
D. Faulkner ◽  
D. J. Cameron
Keyword(s):  
Solid Solution ◽  
Intermetallic Compound ◽  
Phase Transformations ◽  
Single Phase ◽  
Structural Materials ◽  
Al Alloys ◽  
Al Alloy ◽  
Hydrogen System ◽  
A Value ◽  
Al Matrix

Zr-Al alloys based on the intermetallic compound Zr3Al are presently being considered as structural materials for use in nuclear environments. Theoretically, the single-phase Zr3Al alloy should contain 8.97% Al, but in practice single phase material is not produced, and alloys containing approximately 8.0 to 8.5% Al contain a dispersion of α-Zr solid solution in the Zr3Al matrix (fig. 1). At higher Al concentrations Zr2Al may also be present.In this paper we describe the structures observed in a Zr-8.3% Al alloy containing up to 1300 μg/g hydrogen. Hydrogen was introduced into the alloy in two ways. The first technique involved the exposure of a weighed sample, at 650°C to a known volume of hydrogen at a predetermined pressure. The pressure was monitored during hydriding until it dropped to a value corresponding to the required uptake of hydrogen.

scholarly journals Severe Plastic Deformation and Phase Transformations in High Entropy Alloys: A Review

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 54
Author(s):  
Boris B. Straumal ◽  
Roman Kulagin ◽  
Brigitte Baretzky ◽  
Natalia Yu. Anisimova ◽  
Mikhail V. Kiselevskiy ◽  
...  
Keyword(s):  
Solid Solution ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Phase Transformations ◽  
Single Phase ◽  
Materials Science ◽  
Bulk Solution ◽  
Second Phase ◽  
High Entropy Alloys ◽  
High Entropy

This review discusses an area of expertise that is at the intersection of three large parts of materials science. These are phase transformations, severe plastic deformation (SPD), and high-entropy alloys (HEA). First, SPD makes it possible to determine the borders of single-phase regions of existence of a multicomponent solid solution in HEAs. An important feature of SPD is that using these technologies, it is possible to obtain second-phase nanoparticles included in a matrix with a grain size of several tens of nanometers. Such materials have a very high specific density of internal boundaries. These boundaries serve as pathways for accelerated diffusion. As a result of the annealing of HEAs subjected to SPD, it is possible to accurately determine the border temperature of a single-phase solid solution area on the multicomponent phase diagram of the HEA. Secondly, SPD itself induces phase transformations in HEAs. Among these transformations is the decomposition of a single-phase solid solution with the formation of nanoparticles of the second phase, the formation of high-pressure phases, amorphization, as well as spinodal decomposition. Thirdly, during SPD, a large number of new grain boundaries (GBs) are formed due to the crystallites refinement. Segregation layers exist at these new GBs. The concentration of the components in GBs differs from that in the bulk solid solution. As a result of the formation of a large number of new GBs, atoms leave the bulk solution and form segregation layers. Thus, the composition of the solid solution in the volume also changes. All these processes make it possible to purposefully influence the composition, structure and useful properties of HEAs, especially for medical applications.

Analysis of Organizations of Brazed Seam 5052 Al Alloy Contact Reactive Brazing

2013 ◽  
Vol 690-693 ◽  
pp. 2598-2600 ◽  
Author(s):  
Fen Fang Tan ◽  
Kang Du
Keyword(s):  
Solid Solution ◽  
Intermetallic Compound ◽  
Reaction Layer ◽  
Al Alloy ◽  
Layer Material ◽  
Cu Foil ◽  
Ternary Intermetallic Compound ◽  
Binary Intermetallic Compound

Test of 5052 Al alloy contact reactive brazing has been conducted in the case of special brazing parameters, using Cu foil-Mg power-Cu foil as reaction layer material, the microstructure were analyzed and discussed primarily. The results show that the brazing seam structure consisted of α-Al solid solution and CuAl2 intermetallic compound; the organizations of brazed seam include Al (Mg, Cu) solid solution CuAl2 binary intermetallic compound, complicated ternary intermetallic compound and Al2MgO4.

Phase Transformations and Magnetic Properties of Electroplating Ni-Co on Aluminium

2014 ◽  
Vol 487 ◽  
pp. 80-83
Author(s):  
Yong Jun Hu ◽  
Dong Cao ◽  
Xi Qiang Li ◽  
Hui Ting Zheng ◽  
Xiao Ling Cheng ◽  
...  
Keyword(s):  
Solid Solution ◽  
Magnetic Properties ◽  
Magnetic Property ◽  
Phase Transformations ◽  
Intermetallic Compounds ◽  
Alloy Film ◽  
Β Phase ◽  
Al Matrix

In this paper, Ni-Co coatings on Al foil were prepared by electroplating to obtain Al/Ni-Co composite. Phase transformations and magnetic property of Al/Ni-Co composite heated at 823 K for 80 h were investigated. The results showed that obviously exchanged zone in Al matrix exited and the thickness was about 2.5μm. Ni diffused into the Al easilier than Co. β phase (AlNi and AlCo) and γ phase (Al (Ni, Co) solid solution) of Co-Ni-Al formed during the annealing. The Ms of was decreased significantly when Al diffused into the NiCo alloy film and formed Ni-Al and Co-Al intermetallic compounds.

Reversible Hydrogen Absorption/Desorption and Related Lattice Deformation of Ti3Al Based Alloys in the Ti-Al-Nb System

2002 ◽  
Vol 753 ◽  
Author(s):  
Kazuhiro Ito ◽  
Lanting T. Zhang ◽  
Yoshiharu Okabe ◽  
Vijay K. Vasudevan ◽  
Masaharu Yamaguchi
Keyword(s):  
Hydrogen Absorption ◽  
Single Phase ◽  
Al Alloys ◽  
Original Structure ◽  
Al Alloy ◽  
Lattice Deformation ◽  
Hydrogen Atoms ◽  
Two Phase ◽  
Microstructure Effects ◽  
Systematic Understanding

ABSTRACTHydrogen absorption/desorption of Ti3Al-based alloys with α2 single-phase, β0 single-phase and β/O two-phase microstructures was investigated to obtain systematic understanding microstructure effects. On exposing all the alloys to hydrogen, β (βH) and γ (γH) hydrides are formed. The βH and γH have bcc and bct (close to fcc) based structures, respectively. The hydrogen/metal ratio of the γH is larger than that of βH. Thus, solute hydrogen in Ti3Al based alloys stabilizes the bcc-based phase just like Nb, regardless of their original structure before hydrogenation. On the other hand, reversible hydrogen absorption/desorption around 100°C and related reversible βH-γH transformation was observed in β/O two-phase (Ti,Nb)3Al and α2-Ti3Al alloys, but not obviously observed in a β0-(Ti,Nb)3Al alloy. In forming the βH, the expansion of the β0 and β phases occurred isotropically keeping their structures B2 and bcc, respectively. In contrast, the O and α2 phases expanded in anisotropic manner. The lattice deformation for the βH→γH transformation can be described similarly to those for the O→βH and α2→βH transformations. Such lattice deformation in anisotropic manner most likely agrees with that observed in a martensitic displacive transformation, because of the surface relief observed on the γH after the βH→γH transformation in the β0-(Ti,Nb)3Al alloy and many twins formed during the α2→βH transformation in the α2-Ti3Al alloy. Mechanisms of the reversible βH-γH transformation in the β/O two-phase (Ti,Nb)3Al and α2-Ti3Al alloys was proposed on the basis of similarities in the lattice deformation and ordering of hydrogen atoms required for the βH-γH, O-βH and α2-βH transformations.

scholarly journals The Evolution of Intermetallic Compounds in High-Entropy Alloys: From the Secondary Phase to the Main Phase

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2054
Author(s):  
Junqi Liu ◽  
Xiaopeng Wang ◽  
Ajit Singh ◽  
Hui Xu ◽  
Fantao Kong ◽  
...  
Keyword(s):  
Solid Solution ◽  
Intermetallic Compound ◽  
Intermetallic Compounds ◽  
High Performance ◽  
Single Phase ◽  
Secondary Phase ◽  
Main Phase ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
High Entropy

High-performance structural materials are critical to the development of transportation, energy, and aerospace. In recent years, newly developed high-entropy alloys with a single-phase solid-solution structure have attracted wide attention from researchers due to their excellent properties. However, this new material also has inevitable shortcomings, such as brittleness at ambient temperature and thermodynamic instability at high temperature. Efforts have been made to introduce a small number of intermetallic compounds into single-phase solid-solution high-entropy alloys as a secondary phase to their enhance properties. Various studies have suggested that the performance of high-entropy alloys can be improved by introducing more intermetallic compounds. At that point, researchers designed an intermetallic compound-strengthened high-entropy alloy, which introduced a massive intermetallic compound as a coherent strengthening phase to further strengthen the matrix of the high-entropy alloy. Inspired from this, Fantao obtained a new alloy—high-entropy intermetallics—by introducing different alloying elements to multi-principalize the material in a previous study. This new alloy treats the intermetallic compound as the main phase and has advantages of both structural and functional materials. It is expected to become a new generation of high-performance amphibious high-entropy materials across the field of structure and function. In this review, we first demonstrate the inevitability of intermetallic compounds in high-entropy alloys and explain the importance of intermetallic compounds in improving the properties of high-entropy alloys. Secondly, we introduce two new high-entropy alloys mainly from the aspects of composition design, structure, underlying mechanism, and performance. Lastly, the high-entropy materials containing intermetallic compound phases are summarized, which lays a theoretical foundation for the development of new advanced materials.

scholarly journals Evidence of Martensitic Transformation in Fe-Mn-Al Steel Similar to Maraging Steel

2020 ◽  
Vol 52 (1) ◽  
pp. 26-33
Author(s):  
Gurumayum Robert Kenedy ◽  
Yi-Jyun Lin ◽  
Wei-Chun Cheng
Keyword(s):  
Martensitic Transformation ◽  
Maraging Steel ◽  
Trip Steel ◽  
Single Phase ◽  
Lath Martensite ◽  
Al Alloy ◽  
Air Cooling ◽  
Small Temperature Gradient ◽  
Austenite Grains ◽  
Equilibrium Phases

AbstractThe Fe-Mn-Al steels claim a low density, and some fall into the category of transformation-induced plasticity (TRIP) steel. In Fe-Mn-Al TRIP steel development, phase transformations play an important role. Herein, the martensitic transformation of an Fe-16.7 Mn-3.4 Al ternary alloy (wt pct) was experimentally discovered, whose equilibrium phases are a single phase of austenite at 1373 K and dual phases of ferrite and austenite at low temperature. Ferritic lath martensite forms in the prior austenite grains after cooling from 1373 K under various cooling rates via quenching, air cooling, and furnace cooling. The formation mechanism of the ferritic lath martensite is different from that of traditional ferritic lath martensite in steel and quite similar to that in maraging steel. A slight strain energy coupled with a small temperature gradient can lead to the formation of ferritic lath martensite in the Fe-Mn-Al alloy after cooling from high temperature. It is also found that micro-twins exist in the ferritic lath martensite.

Influence of ageing treatment on microstructure, mechanical properties and adhesive wear behaviour of 6063 aluminium alloy

2014 ◽  
Vol 66 (4) ◽  
pp. 520-524 ◽  
Author(s):  
Serkan Büyükdoğan ◽  
Süleyman Gündüz ◽  
Mustafa Türkmen
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
High Speed ◽  
Al Alloys ◽  
Wear Behaviour ◽  
Al Alloy ◽  
Strain Ageing ◽  
Content Type ◽  
Static Strain ◽  
Structural Applications

Purpose – The paper aims to provide new observations about static strain ageing in aluminium (Al) alloys which are widely used in structural applications. Design/methodology/approach – The present work aims to provide theoretical and practical information to industries or researchers who may be interested in the effect of static strain ageing on mechanical properties of Al alloys. The data are sorted into the following sections: introduction, materials and experimental procedure, results and discussion and conclusions. Findings – Tensile strength, proof strength (0.2 per cent) and percentage elongation measurement were used to investigate the effect of strain ageing on the mechanical properties. Wear tests were performed by sliding the pin specimens, which were prepared from as-received, solution heat-treated, deformed and undeformed specimens after ageing, on high-speed tool steel (64 HRC). It is concluded that the variations in ageing time improved the strength and wear resistance of the 6063 Al alloy; however, a plastically deformed solution-treated alloy has higher strength and wear resistance than undeformed specimens for different ageing times at 180°C. Practical implications – A very useful source of information for industries using or planning to produce Al alloys. Originality/value – This paper fulfils an identified resource need and offers practical help to the industries.

Direct Cladding from Molten Metals of Aluminum and Magnesium Alloys Using a Tandem Horizontal Twin Roll Caster

2015 ◽  
Vol 772 ◽  
pp. 250-256 ◽  
Author(s):  
Hideto Harada ◽  
Shin Ichi Nishida ◽  
Mayumi Suzuki ◽  
Hisaki Watari ◽  
T. Haga
Keyword(s):  
Surface Condition ◽  
Hardness Test ◽  
Al Alloys ◽  
Mg Alloy ◽  
Al Alloy ◽  
Molten Metals ◽  
Electron Probe Micro Analyzer ◽  
Twin Roll Caster ◽  
Aluminum And Magnesium Alloys ◽  
Twin Roll

This paper describes direct cladding of magnesium (Mg) and aluminum (Al) alloys using a tandem horizontal twin roll caster that has three pairs of upper and lower rolls. Manufacturing conditions that are appropriate for fabricating Al/Mg and Al/Mg/Al cladded material were investigated. The surface condition of the cladded cast strip was examined. An electron probe micro analyzer was used to observe the interface between Al alloy and Mg alloy. The thickness of the mixed layer of Al and Mg alloy was 15μm, and how the materials were connected was clarified. Microscopic observation and backscattered electron analysis were used to investigate the cladding mechanisms of the Al and Mg alloy layers. Average hardness was determined using the Vickers hardness test at the Al layer and at the diffused layer between Mg and Al alloys. Cladding of Al/Mg alloy and A/Mg/Al alloy was possible using a tandem twin-roll caster. In addition, Al3Mg2 and Al12Mg17 phase precipitation at the interface of the Al and Mg alloys was confirmed during direct cladding from molten metals.

scholarly journals Mechanical Properties of Al Matrix Composite Enhanced by In Situ Formed SiC, MgAl2O4, and MgO via Casting Process

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1767
Author(s):  
Yuhong Jiao ◽  
Jianfeng Zhu ◽  
Xuelin Li ◽  
Chunjie Shi ◽  
Bo Lu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Matrix Composite ◽  
Compression Strength ◽  
Casting Process ◽  
Al Alloy ◽  
Pyrolysis Process ◽  
Alloy Matrix ◽  
Al Matrix Composite ◽  
Al Matrix

Al matrix composite, reinforced with the in situ synthesized 3C–SiC, MgAl2O4, and MgO grains, was produced via the casting process using phenolic resin pyrolysis products in flash mode. The contents and microstructure of the composites’ fracture characteristics were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties were tested by universal testing machine. Owing to the strong propulsion formed in turbulent flow in the pyrolysis process, nano-ceramic grains were formed in the resin pyrolysis process and simultaneously were homogeneously scattered in the alloy matrix. Thermodynamic calculation supported that the gas products, as carbon and oxygen sources, had a different chemical activity on in situ growth. In addition, ceramic (3C–SiC, MgAl2O4, and MgO) grains have discrepant contents. Resin pyrolysis in the molten alloy decreased oxide slag but increased pores in the alloy matrix. Tensile strength (142.6 ± 3.5 MPa) had no change due to the cooperative action of increased pores and fine grains; the bending and compression strength was increasing under increased contents of ceramic grains; the maximum bending strength was 378.2 MPa in 1.5% resin-added samples; and the maximum compression strength was 299.4 MPa. Lath-shaped Si was the primary effect factor of mechanical properties. The failure mechanism was controlled by transcrystalline rupture mechanism. We explain that the effects of the ceramic grains formed in the hot process at the condition of the resin exist in mold or other accessory materials. Meanwhile, a novel ceramic-reinforced Al matrix was provided. The organic gas was an excellent source of carbon, nitrogen, and oxygen to in situ ceramic grains in Al alloy.

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