scholarly journals Influence of magnesium on high-temperature structural-phase stability of Al-Ni-La system alloys

2021 ◽  
Vol 98 (2) ◽  
pp. 38-46
Author(s):  
M. M. Voron ◽  
Keyword(s):  
Elevated Temperatures ◽  
Structural Phase ◽  
Nickel Content ◽  
Magnesium Content ◽  
Cast State ◽  
Lanthanum Content ◽  
Cast Alloys ◽  
Cast Condition ◽  
Alloys Of The Al ◽  
Eutectic Component

The paper considers a relevance of the Al-Ni-La system cast alloys development as promising materials for application at elevated temperatures. The influence of magnesium on the structural-phase characteristics of alloys-representatives with a nickel content of about 2% wt. and lanthanum - about 5,5 and 11,5% wt. were studied in the cast condition and after annealing at 425 ° C for 5 hours. It is shown, that the addition of magnesium in the amount of 0,6 wt%. to alloys with a lanthanum content of 5,5 % wt. helps to increase the size of the lanthanum-containing eutectic component in the cast state, but stimulates its grinding after annealing. Since doubling the lanthanum content, magnesium has almost no effect on the structure of the eutectic in the cast state, but intensifies the process of changing its structure during annealing. In this case, the size of the eutectic components is almost unchanged and can be compared with an undoped alloy. Increasing the magnesium content twice to 1,2% wt. in the alloy with a lanthanum content of 11% wt. leads to a noticeable enlargement of Al11La3 intermetallics. After annealing, this structural component retains the characteristics of a fibrous structure and at the same time increases in size by about half. The magnesium content in the eutectic zones and in the solid solution hardly changes after annealing. The obtained data indicate the possibility of using magnesium as an additional alloying element of cast heat-resistant alloys of the Al-Ni-La system, which is able to simultaneously contribute to their strengthening both under normal conditions and at elevated temperatures. In this case, magnesium, in the amount of about 0,6% wt., also helps to preserve the fine structure of the eutectic components at high temperatures. Keywords: Al-Ni-La, Al-Ni-La-Mg, alloying, structural stability, heat resistance.

Structure and mechanical properties of cast quasicrystal-reinforced Mg–Zn–Al–Y base alloys

2004 ◽  
Vol 19 (5) ◽  
pp. 1531-1538 ◽  
Author(s):  
Guangyin Yuan ◽  
Kenji Amiya ◽  
Hidemi Kato ◽  
Akihisa Inoue
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Cast Alloy ◽  
Strengthening Mechanism ◽  
Icosahedral Quasicrystal ◽  
Compression Tests ◽  
Strengthening Phase ◽  
Creep Tests ◽  
Cast Alloys ◽  
Bulk Alloys

The structure and mechanical properties of Mg–Zn–Al–Y base cast alloys containing an icosahedral quasicrystal phase (i-phase) as a main strengthening phase were investigated. Mg–8Zn–4Al–xY base bulk alloys containing the i-phase were prepared by casting into a copper mold at moderate cooling rates. The Y addition was effective for decreasing the size of the i-phase and the increasing the homogeneity of its dispersed state. The mechanical properties examined by compression tests at room temperature were much superior to those of a conventional AZ91 Mg alloy. The creep tests at elevated temperatures indicated a promising high temperature creep resistance of the quasicrystal-reinforced Mg–Zn–Al–Y cast alloy. The strengthening mechanism was also discussed.

scholarly journals The Dilatometric Analysis of the High Carbon Alloys from Ni-Ta-Al-M System

2014 ◽  
Vol 59 (3) ◽  
pp. 977-980 ◽  
Author(s):  
P. Bała
Keyword(s):  
Elevated Temperatures ◽  
Volume Fraction ◽  
Intermetallic Phase ◽  
Coarse Grained ◽  
Precipitation Process ◽  
Cast State ◽  
High Carbon ◽  
Chromium Carbides ◽  
Tantalum Carbides ◽  
Co Alloys

Abstract In the following work presents results of high carbon alloys from the Ni-Ta-Al-M system are presented. The alloys have been designed to have a good tribological properties at elevated temperatures. Despite availability of numerous hot work tool materials there is still a growing need for new alloys showing unique properties, which could be used under heavy duty conditions, i.e. at high temperatures, in a chemically aggressive environment and under heavy wear conditions. A characteristic, coarse-grained dendritic microstructure occurs in the investigated alloys in the as-cast condition. Primary dendrites with secondary branches can be observed. Tantalum carbides of MC type and graphite precipitations are distributed in interdendritic spaces in the Ni-Ta-Al-C and Ni-Ta-Al-C-Co alloys, while Tantalum carbides of MC type and Chromium carbides of M7C3 type appeared in the Ni-Ta-Al-C-Co-Cr and Ni-Ta-Al-C-Cr alloys. In all alloys g’ phase is present, however, its volume fraction in the Ni-Ta-Al-C and Ni-Ta-Al-C-Co alloys is small.During heating from as-cast state in Ni-Ta-Al-C and Ni-Ta-Al-C-Co alloys, the beginning of the tantalum carbides precipitation process (MC type) followed (or simultaneous) by the intermetallic phase precipitation (g’ – Ni3(AlTa)) was stated, while in Ni-Ta-Al-C-Co-Cr and Ni-Ta-Al-C-Cr alloys, besides Tantalum carbides also the Chromium carbides precipitation occurred. It means that the investigated alloys were partially supersaturated in as-cast state. Above 1050°C in all investigated alloys the g’ phase is dissolving. In addition, the precipitation of secondary carbides during slow cooling was occured.

scholarly journals Laser Beam Welding of a Low Density Refractory High Entropy Alloy

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1351 ◽  
Author(s):  
Evgeniya Panina ◽  
Nikita Yurchenko ◽  
Sergey Zherebtsov ◽  
Nikita Stepanov ◽  
Gennady Salishchev ◽  
...  
Keyword(s):  
Laser Beam ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Laser Beam Welding ◽  
Base Material ◽  
Laves Phase ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Grains Refinement ◽  
Cast Condition

The effect of laser beam welding on the structure and properties of a Ti1.89NbCrV0.56 refractory high entropy alloy was studied. In particular, the effect of different pre-heating temperatures was examined. Due to the low ductility of the material, laser beam welding at room temperature resulted in the formations of hot cracks. Sound butt joints without cracks were produced using pre-heating to T ≥ 600 °C. In the initial as-cast condition, the alloy consisted of coarse bcc grains with a small amount of lens-shaped C15 Laves phase particles. A columnar microstructure was formed in the welds; the thickness of the grains increased with the temperature of pre-heating before welding. The Laves phase particles were formed in the seams after welding at 600 °C or 800 °C, however, these particles were not observed after welding at room temperature or at 400 °C. Soaking at elevated temperatures did not change the microstructure of the base material considerably, however, “additional” small Laves particles formed at 600 °C or 800 °C. Tensile test of welded specimens performed at 750 °C resulted in the fracture of the base material because of the higher hardness of the welds. The latter can be associated with the bcc grains refinement in the seams.

DC Casting, Deformation and Strengthening of Al-Si Alloys

2012 ◽  
Vol 706-709 ◽  
pp. 186-193 ◽  
Author(s):  
Liang Zuo ◽  
Fu Xiao Yu
Keyword(s):  
Mechanical Properties ◽  
Direct Chill ◽  
Cast State ◽  
The Poor ◽  
Low Thermal Expansion ◽  
Cast Alloys ◽  
Superior Mechanical Properties ◽  
Deformation And Heat Treatment ◽  
Dc Casting ◽  
Strength And Ductility

Al-Si alloys are widely used as cast alloys for their excellent castability, low thermal expansion coefficient, good wear resistance and corrosion resistance properties. However, the poor ductility of these alloys, caused by the presence of coarse and non-deformable Si phase in the as-cast state, has inhibited their applications as wrought materials. Recently, a process based on traditional technologies, i.e., direct chill (DC) casting followed by hot deformation and heat treatment, has been developed for potential mass production of wrought Al-Si alloys with superior mechanical properties in view of their strength and ductility. In this work, the microstructural evolutions of DC cast Al-Si alloys involved in solidification, recrystallization and precipitation during the processing are highlighted, aiming at understanding the correlations between the microstructures and the mechanical properties.

Microstructural and Magnetic Improvements in Tube-Cast Pr-Fe-B-Cu Alloys Via Heat Treatments and Rapid Upset Forging

1999 ◽  
Vol 577 ◽  
Author(s):  
G P Hatch ◽  
A J Williams ◽  
I R Harris
Keyword(s):  
Magnetic Properties ◽  
Heat Treatments ◽  
Cast State ◽  
Steel Tubes ◽  
Cu Alloys ◽  
Upset Forging ◽  
Cast Alloys ◽  
Optimum Heat ◽  
Alternative Routes ◽  
Optimum Heat Treatment

ABSTRACTAlloys of Pr-Fe-B-Cu were cast into Cu and stainless steel tubes. It could be seen that a preferred crystallographic orientation was obtained after cooling. Fine platelets of Pr2Fe1 4B matrix phase were formed, surrounded by various grain boundary phases, and there was a significant reduction in the amount of free Fe present, in comparison to conventional slab cast alloys. In order to improve the magnetic properties in the as-cast state, two alternative routes were used. The first involved a series of two step heat treatments to develop an improved microstructure. After an optimum heat treatment of 1000 'C for 24 hours + 500°C for 3 hours, significantly improved magnetic properties were obtained for a 17.5 % Pr alloy; Br = 752 mT, Hci = 613 kAm−1 and BHmax = 96 kJm−3. The second route involved a rapid upset forging [RUF] process, with a strain rate of 11.5 s−1, to hot deform the alloys. Following post-forging heat treatments, properties of Br = 966 mT, Hci = 780 kAm−3 and BHmax = 160 kJm−3 were obtained for a 15% Pr alloy. That nature of the improvements in properties as a result of heat treatments and RUF were investigated and are discussed in the present work.

Erosion of ferritic FeCrC cast alloys at elevated temperatures

Wear ◽  
1997 ◽  
Vol 211 (1) ◽  
pp. 120-128 ◽  
Author(s):  
A. Drotlew ◽  
P. Christodoulou ◽  
V. Gutowski
Keyword(s):  
Elevated Temperatures ◽  
Cast Alloys

Microstructure Characterization of High Carbon Alloy from the Ni-Ta-Al-Co-Cr System / Charakterystyka Mikrostruktury Wysokowęglowego Stopu Z Układu Ni-Ta-Al-Co-Cr

2012 ◽  
Vol 57 (4) ◽  
pp. 937-941 ◽  
Author(s):  
P. Bała
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Elevated Temperatures ◽  
Chromium Content ◽  
Volume Fraction ◽  
High Carbon ◽  
Cr System ◽  
Primary Carbides ◽  
Cast Condition

In the present work results of investigations of the new high carbon alloy from the Ni-Ta-Al-Co-Cr system are presented. The alloy has been designed to have a good tribological properties at elevated temperatures. The chemical composition of this material was designed to obtain a matrix strengthening by the precipitation of γ’ phase (Ni3(Al,Ta)) and the primary carbides volume fraction above 25%. The primary carbides should remain stable in the microstructure, regardless of the heat treatment, in order to increase a wear resistance. The results of microstructure investigations in the as-cast condition are presented. The type of phases appearing in the microstructure was determined and their morphology described. The main microstructure components of the investigated Ni-based alloy with high carbon, cobalt and chromium content are: the γ phase, which constitutes a matrix, the γ’ phase, which occurs as fine globular precipitates and the primary Ta and Cr carbides (of MC and M7C3 type - respectively).

The Effect of Ni on the High-Temperature Strength of Al-Si Cast Alloys

2011 ◽  
Vol 690 ◽  
pp. 274-277 ◽  
Author(s):  
Florian Stadler ◽  
Helmut Antrekowitsch ◽  
Werner Fragner ◽  
Helmut Kaufmann ◽  
Peter J. Uggowitzer
Keyword(s):  
High Temperature ◽  
Load Transfer ◽  
Elevated Temperatures ◽  
Close Contact ◽  
Sem Analysis ◽  
High Temperature Strength ◽  
Phase System ◽  
Two Phase ◽  
Eutectic Si ◽  
Cast Alloys

In order to investigate the effect of Ni on the high-temperature strength of Al-Si cast alloys, tensile properties of hypoeutectic and eutectic alloys were determined at 250 °C after long-term annealing at test temperature. LOM- and SEM-analysis revealed the existence of Al3Ni-phases in close contact to eutectic Si. It was shown that the strength can be increased by the addition of Ni, though just to a certain level, depending on the fraction of eutectic phase in the alloy. The alloys were considered as a coarse two-phase system where a hardening effect is caused by load transfer to the harder phase, which requires a certain connectivity/contiguity of the latter. The paper describes the extent of contiguity of the eutectic as well as the hard silicon and Al3Ni-phases within the eutectic, and discusses their contribution to an enhanced strength of Al-Si alloys at elevated temperatures.

Influence of Aluminium Content on Behaviour of Magnesium Cast Alloys in Bentonite Sand Mould

2009 ◽  
Vol 147-149 ◽  
pp. 764-769 ◽  
Author(s):  
Leszek Adam Dobrzański ◽  
Tomasz Tański
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Chemical Composition ◽  
Physical And Mechanical Properties ◽  
Aluminium Content ◽  
Cast State ◽  
Cast Alloys ◽  
Cast Magnesium Alloys ◽  
Cast Magnesium ◽  
Cooling Methods

In this paper there is presented the structure and proprieties of the modeling cast magnesium alloys as cast state and after heat treatment, depending on the cooling medium (furnace, water, air), with different chemical composition. The improvement of the manufacturing technique and chemical composition as well as of heat treatment and cooling methods leads to the development of a material designing process for the optimal physical and mechanical properties of a new developed alloy. In the analysed alloys a structure of solid solution and fragile phase  (Mg17Al12) occurred mainly on grain borders as well as eutectic and AlMnFe, Mg2Si phase. The investigation is carried out to testy the influence of the chemical composition and precipitation processes on the structure and mechanical properties of the magnesium cast alloys with different chemical composition in its as cast alloys and after heat treatment.

Effect of Heat Treatment on Phase Composition and Microstructure of Al-Cu-Fe Alloys with Quasicrystalline Phases

2014 ◽  
Vol 794-796 ◽  
pp. 833-838
Author(s):  
Marina Samoshina ◽  
Pavel Bryantsev
Keyword(s):  
Heat Treatment ◽  
Phase Composition ◽  
Quasicrystalline Phase ◽  
Cast State ◽  
Equilibrium Conditions ◽  
Crystalline Phases ◽  
Different Temperatures ◽  
Fe Alloys ◽  
Cast Condition

The microstructure and phase composition of alloys Al-Cu-Fe in as-cast state and after heat treatment at different temperatures were investigated. The presence of a quasicrystalline phase Al65Cu20Fe15 which coexists with crystalline phases in as-cast condition is found. The formation of single quasicrystalline phase composition in Al - 40 wt.% Cu - 17 wt.% Fe alloy after annealing at 800 °C for 100 hours is established. After heat treatment, i.e. closer to equilibrium conditions, the quasicrystalline phase Al65Cu20Fe15 is transformed into quasicrystalline phase Al13Cu4Fe3 with more complicated lattice.

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