The structure and stability of some intermetallic phases in rapidly solidified AlFe

1988 ◽  
Vol 22 (6) ◽  
pp. 797-802 ◽  
Author(s):  
M. Chandrasekaran ◽  
Y.P. Lin ◽  
R. Vincent ◽  
G. Staniek
Keyword(s):  
Intermetallic Phases ◽  
Structure And Stability ◽  
Rapidly Solidified

Formation of Quasicrystals In Rapidly Solidified Al Alloys

1985 ◽  
Vol 58 ◽  
Author(s):  
Robert J. Schaefer ◽  
Leonid A Bendersky
Keyword(s):  
Electron Beam ◽  
Electron Beam Melting ◽  
Icosahedral Phase ◽  
Intermetallic Phases ◽  
Moderate Growth ◽  
Wide Range ◽  
Beam Surface ◽  
Equilibrium Phases ◽  
Rapidly Solidified ◽  
T Phase

ABSTRACTElectron beam surface melting has been used to study Al-Mn and Al-Mn-Si alloys subjected to a wide range of solidification conditions. Several of the reported equilibrium intermetallic phases are not found even at moderate growth rates. Beyond a composition-dependent critical velocity the equilibrium phases are all replaced by the quasicrystalline icosahedral and decagonal (T) phases. The icosahedral phase is favored over the T phase by higher solidification velocities. The addition of Si to Al-Mn alloys eliminates the T phase, but does not significantly facilitate the formation of the icosahedral phase by electron beam melting because the ternary α and β phases of Al-Mn-Si are able to grow rapidly into the electron beam melts.

Structure and stability of rapidly solidified Al—Si based alloys

1986 ◽  
Vol 5 (5) ◽  
pp. 586-588 ◽  
Author(s):  
C. Antonione ◽  
L. Battezzati ◽  
F. Marino
Keyword(s):  
Structure And Stability ◽  
Rapidly Solidified

scholarly journals Rapidly Solidified Aluminium Alloy Composite with Nickel Prepared by Powder Metallurgy: Microstructure and Self-Healing Behaviour

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4193 ◽  
Author(s):  
Alena Michalcová ◽  
Anna Knaislová ◽  
Jiří Kubásek ◽  
Zdeněk Kačenka ◽  
Pavel Novák
Keyword(s):  
Yield Strength ◽  
Intermetallic Phases ◽  
Ultimate Tensile Stress ◽  
Self Healing ◽  
Offset Yield Strength ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Pass Through ◽  
Rapidly Solidified ◽  
Al Matrix

Composite material prepared by spark plasma sintering (SPS) from a powder mixture of AlCrFeSi rapidly solidified alloy and 5 wt. % of Ni particles was studied in this work. It was proven that during SPS compaction at 500 °C, no intermetallic phases formed on the surface of Ni particles. The material exhibited sufficient mechanical properties obtained by tensile testing (ultimate tensile stress of 203 ± 4 MPa, ductility of 0.8% and 0.2% offset yield strength of 156 ± 2 MPa). Tensile samples were pre-stressed to 180 MPa and annealed at 450 and 550 °C for 1 h. Annealing at 450 °C did not lead to any recovery of the material. Annealing at 550 °C caused the full recovery of 0.2% offset yield strength, while the ductility was decreased. The self-healing behaviour originates from the growth of intermetallic phases between the Ni particle and the Al matrix. The sequence of NiAl, Ni2Al3 and NiAl3 intermetallic phases formation was observed. In particular, the morphology of the NiAl3 phase, growing in thin dendrites into the Al matrix, is suitable for the closing of cracks, which pass through the material.

Effect of RE Elements and Ni Contents on the Microstructure and Mechanical Properties of Rapidly Solidified Mg Ribbons

2007 ◽  
Vol 539-543 ◽  
pp. 1662-1668 ◽  
Author(s):  
Sergio Gonzáles ◽  
P. Pérez ◽  
G. Garcés ◽  
P. Adeva
Keyword(s):  
Mechanical Properties ◽  
Amorphous State ◽  
Intermetallic Phases ◽  
Mechanical Resistance ◽  
Crystalline Materials ◽  
Intermetallic Matrix ◽  
Microstructure And Mechanical Properties ◽  
Matrix Embedding ◽  
Rapidly Solidified ◽  
Re Elements

The effect of the concentration of Ni, Y and La-rich mischmetal on the thermal stability, microstructure and mechanical properties of ribbons tested in the temperature range 25-350°C have been evaluated. The low-alloyed materials were crystalline or partially crystalline while high-alloyed materials were amorphous. The amorphous alloys experienced numerous transformations during heating above 170°C. A transition in the amorphous state was observed in all alloys prior to the crystallization stage. The alloy composition determines the sequence of phase transformations during crystallization. In general, the structure of crystallised amorphous, even at high temperatures, is much finer than that of crystalline materials. A MgxREy intermetallic matrix with other intermetallic phases homogeneously distributed was observed in the crystallised ribbons with high RE contents. However, a magnesium matrix embedding other intermetallic phases was the microstructure observed for low-alloyed materials. The amorphous Mg-10Ni-2.5Y2.5-2.5La(MM) showed the higher tensile strength values up to 200 °C The crystalline Mg-2Ni-1Y-1La(MM) ribbon and the partially crystalline Mg-3Ni-1.5Y-1.5La(MM) alloy also exhibited high mechanical resistance levels which were maintained up to 250 °C. MgNi10Y2.5La(MM)2.5 amorphous and MgNi3Y1.5La(MM)1.5 crystalline broken above 500 and 400 MPa, respectively, at 100°C

Suppression of γ’ Precipitation in a Laser-Melted Nickel-Base Alloy

1977 ◽  
Vol 35 ◽  
pp. 270-271
Author(s):  
J. M. Walsh ◽  
J. C. Whittles ◽  
B. H. Kear ◽  
E. M. Breinan
Keyword(s):  
Cooling Rate ◽  
Base Alloy ◽  
Material Surface ◽  
Intimate Contact ◽  
Absorbed Power ◽  
Perfect Contact ◽  
Nickel Base ◽  
Rapidly Solidified ◽  
Limiting Case ◽  
The Heat Transfer Coefficient

Conventionally cast γ’ precipitation hardened nickel-base superalloys possess well-defined dendritic structures and normally exhibit pronounced segregation. Splat quenched, or rapidly solidified alloys, on the other hand, show little or no evidence for phase decomposition and markedly reduced segregation. In what follows, it is shown that comparable results have been obtained in superalloys processed by the LASERGLAZE™ method.In laser glazing, a sharply focused laser beam is traversed across the material surface at a rate that induces surface localized melting, while avoiding significant surface vaporization. Under these conditions, computations of the average cooling rate can be made with confidence, since intimate contact between the melt and the self-substrate ensures that the heat transfer coefficient is reproducibly constant (h=∞ for perfect contact) in contrast to the variable h characteristic of splat quenching. Results of such computations for pure nickel are presented in Fig. 1, which shows that there is a maximum cooling rate for a given absorbed power density, corresponding to the limiting case in which melt depth approaches zero.

On the Origin of the Microscystalline Structure in Rapidly Solidified IN-100 Powder

1977 ◽  
Vol 35 ◽  
pp. 260-261
Author(s):  
J. M. Walsh ◽  
K. P. Gumz ◽  
J. C. Whittles ◽  
B. H. Kear
Keyword(s):  
The Other ◽  
Coarse Grained ◽  
Microcrystalline Structure ◽  
Routine Examination ◽  
Atomization Process ◽  
Centrifugal Atomization ◽  
Splat Quenching ◽  
Powder Particles ◽  
Dendritic Microstructures ◽  
Rapidly Solidified

During a routine examination of the microstructure of rapidly solidified IN-100 powder, produced by a newly-developed centrifugal atomization process1, essentially two distinct types of microstructure were identified. When a high melt superheat is maintained during atomization, the powder particles are predominantly coarse-grained, equiaxed or columnar, with distinctly dendritic microstructures, Figs, la and 4a. On the other hand, when the melt superheat is reduced by increasing the heat flow to the disc of the rotary atomizer, the powder particles are predominantly microcrystalline in character, with typically one dendrite per grain, Figs, lb and 4b. In what follows, evidence is presented that strongly supports the view that the unusual microcrystalline structure has its origin in dendrite erosion occurring in a 'mushy zone' of dynamic solidification on the disc of the rotary atomizer.The critical observations were made on atomized material that had undergone 'splat-quenching' on previously solidified, chilled substrate particles.

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