Microstructure and Mechanical Properties of a Single Crystal NiAl Alloy with Zr or HF Rich G-Phase Precipitates.

ABSTRACTThe possibility of producing NiAl reinforced with the G-phase (Ni16X6Si7), where X is Zr or Hf, has been investigated. The microstructures of these NiAl alloys have been characterized in the as-cast and annealed conditions. The G-phases are present as fine cuboidal precipitates (10 to 40 nm) and have lattice parameters almost four times that of NiAl. They are coherent with the matrix and fairly resistant to coarsening during annealing heat treatments. Segregation and non-uniform precipitate distribution observed in as-cast materials were eliminated by homogenization at temperatures near 1600 K. Slow cooling from these temperatures resulted in large plate shaped precipitates, denuded zones, and a loss of coherency in some of the large particles. Faster cooling produced a homogeneous fine distribution of cuboidal G-phase particles (≤10 nm) in the matrix. Preliminary mechanical properties for the Zr-doped alloy are presented and compared to binary single crystal NiAl. The presence of these precipitates appears to have an important strengthening effect at temperatures≥1000 K compared to binary NiAl single crystals.

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Growth of single crystals in the (Na1/2Bi1/2)TiO3–(Sr1–xCax)TiO3 system by solid state crystal growth

Journal of Advanced Ceramics ◽

10.1007/s40145-021-0481-2 ◽

2021 ◽

Author(s):

Phan Gia Le ◽

Huyen Tran Tran ◽

Jong-Sook Lee ◽

John G. Fisher ◽

Hwang-Pill Kim ◽

...

Keyword(s):

Crystal Growth ◽

Solid State ◽

Single Crystal ◽

Single Crystals ◽

Piezoelectric Properties ◽

Single Crystal Growth ◽

Crystal Growth Rate ◽

Large Strains ◽

Growth Technique ◽

The Matrix

AbstractCeramics based on (Na1/2B1/2)TiO3 are promising candidates for actuator applications because of large strains generated by an electric field-induced phase transition. For example, the (1−x)(Na1/2Bi1/2)TiO3-xSrTiO3 system exhibits a morphotropic phase boundary at x = 0.2–0.3, leading to high values of inverse piezoelectric constant d*33, which can be further improved by the use of single crystals. In our previous work, single crystals of (Na1/2B1/2)TiO3-SrTiO3 and (Na1/2B1/2)TiO3-CaTiO3 were grown by the solid state crystal growth technique. Growth in the (Na1/2B1/2)TiO3-SrTiO3 system was sluggish whereas the (Na1/2B1/2)TiO3-CaTiO3 single crystals grew well. In the present work, 0.8(Na1/2Bi1/2)TiO3-0.2(Sr1−xCax)TiO3 single crystals (with x = 0.0, 0.1, 0.2, 0.3, 0.4) were produced by the solid state crystal growth technique in an attempt to improve crystal growth rate. The dependence of mean matrix grain size, single crystal growth distance, and electrical properties on the Ca concentration was investigated in detail. These investigations indicated that at x = 0.3 the matrix grain growth was suppressed and the driving force for single crystal growth was enhanced. Replacing Sr with Ca increased the shoulder temperature Ts and temperature of maximum relative permittivity Tmax, causing a decrease in inverse piezoelectric properties and a change from normal to incipient ferroelectric behavior.

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Influences of the γ′ Phase on the Mechanical Properties of a Nickel-Based Single Crystal Superalloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1023.45 ◽

2021 ◽

Vol 1023 ◽

pp. 45-52

Author(s):

Xiao Yan Wang ◽

Meng Li ◽

Zhi Xun Wen

Keyword(s):

Mechanical Properties ◽

Solid Solution ◽

Single Crystal ◽

Tensile Properties ◽

Room Temperature ◽

Solution Treatment ◽

Single Crystal Superalloy ◽

Original Material ◽

Solid Solution Treatment ◽

The Matrix

After solid solution treatment at 1335°C for 4 hours and cooling to room temperature at different rate, the nickel-based single crystal superalloy were made into three kinds of nickel-based single crystal superalloy materials containing different size γ′ phases, respectively. The tensile test of I-shaped specimens was carried out at 980°C, and their effect of γ′ phase microstructure on the tensile properties was studied. The results show that the yielding strength of the material air-cooled to room temperature was lower than that with cooling rate at 0.15°C/s, but both of them were lower than the yielding strength of original material. Little difference was found on the elastic modulus of I-shaped specimens made of three kinds of materials. When the cubic degree of the γ′ phase is higher and the size is larger, the tensile properties of the material is better, which can be attributed to the larger size and narrower channel of the matrix phase that lead to higher dislocation resistance.

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The Effect of Solid Solution Impurities on Dislocation Nucleation in a (001) Mo – 1.5 at.% Ir Single Crystal

Materials Science Forum ◽

10.4028/www.scientific.net/msf.662.85 ◽

2010 ◽

Vol 662 ◽

pp. 85-93

Author(s):

Sergey Dub ◽

Igor Zasimchuk ◽

Leonid Matvienko

Keyword(s):

Mechanical Properties ◽

Solid Solution ◽

Shear Stress ◽

Elastic Modulus ◽

Single Crystal ◽

Single Crystals ◽

Free Volume ◽

Dislocation Nucleation ◽

Initial Portion ◽

G 12

Mechanical properties of (001) Mo and (001) Mo – 1.5 at.% Ir single crystals have been studied by nanoindentation. It has been found that the iridium addition to molybdenum leads to an increase in both hardness and elastic modulus. An abrupt elasto-plastic transition (pop-in) at a depth of about 20 - 40 nm caused by dislocation nucleation in previously dislocation-free volume has been observed in the initial portion of the loading curve. It has shown that the Ir addition essentially affects the dislocation nucleation. Mean shear stress required for the dislocation nucleation increased from 10.8 GPa (G/12) for a Mo single crystal to 18.2 GPa (G/8) for the Mo – 1.5 at% Ir solid solution. Thus, the Ir solution in a Mo single crystal affects not only the resistance to the motion of dislocations (hardness) but the nucleation of them as well. The latter is likely to occur as a result of an increase in the structure perfection of the Mo – 1.5 at% Ir solid solution as compared to the pure Mo single crystal.

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Micro pulling down growth of very thin shape memory alloys single crystals

Functional Materials Letters ◽

10.1142/s1793604717400033 ◽

2017 ◽

Vol 10 (01) ◽

pp. 1740003 ◽

Cited By ~ 1

Author(s):

I. López-Ferreño ◽

J. San Juan ◽

T. Breczewski ◽

G. A. López ◽

M. L. Nó

Keyword(s):

Mechanical Properties ◽

Shape Memory Alloys ◽

Single Crystal ◽

Shape Memory ◽

Single Crystals ◽

Functional Materials ◽

Small Scale ◽

Cylindrical Shape ◽

Minimum Diameter ◽

Wide Range

Shape memory alloys (SMAs) have attracted much attention in the last decades due to their thermo-mechanical properties such as superelasticity and shape memory effect. Among the different families of SMAs, Cu–Al–Ni alloys exhibit these properties in a wide range of temperatures including the temperature range of 100–200[Formula: see text]C, where there is a technological demand of these functional materials, and exhibit excellent behavior at small scale making them more competitive for applications in Micro Electro-Mechanical Systems (MEMS). However, polycrystalline alloys of Cu-based SMAs are very brittle so that they show their best thermo-mechanical properties in single-crystal state. Nowadays, conventional Bridgman and Czochralski methods are being applied to elaborate single-crystal rods up to a minimum diameter of 1[Formula: see text]mm, but no works have been reported for smaller diameters. With the aim of synthesizing very thin single-crystals, the Micro-Pulling Down ([Formula: see text]-PD) technique has been applied, for which the capillarity and surface tension between crucible and the melt play a critical role. The [Formula: see text]-PD method has been successfully applied to elaborate several cylindrical shape thin single-crystals down to 200[Formula: see text][Formula: see text]m in diameter. Finally, the martensitic transformation, which is responsible for the shape memory properties of these alloys, has been characterized for different single-crystals. The experimental results evidence the good quality of the grown single-crystals.

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Chains of Condensed RuSm6/2 Octahedra in Sm3RuMg7 – A Ternary Ordered Version of the Ti6Sn5 Type

Zeitschrift für Naturforschung B ◽

10.1515/znb-2011-0603 ◽

2011 ◽

Vol 66 (6) ◽

pp. 565-569 ◽

Cited By ~ 1

Author(s):

Stefan Linsinger ◽

Rainer Pöttgen

Keyword(s):

Intermetallic Compound ◽

Single Crystal ◽

Single Crystals ◽

Polycrystalline Sample ◽

Induction Melting ◽

X Ray Diffraction ◽

Slow Cooling ◽

X Ray ◽

Distorted Octahedral ◽

Trigonal Prisms

The magnesium-rich intermetallic compound Sm3RuMg7 was synthesized by induction melting of the elements. Single crystals were grown by slow cooling of the polycrystalline sample. The structure was characterized by powder and single-crystal X-ray diffraction: ordered Ti6Sn5 type, P63/mmc, Z = 2, a = 1034.1(2), c = 611.3(1) pm, wR2 = 0.0216, 399 F2 values and 19 parameters. The ruthenium atoms have slightly distorted octahedral samarium coordination. These RuSm6/2 octahedra (Ru-Sm 279 pm) are condensed via common faces leading to chains in the c direction which are arranged in the form of a hexagonal rod packing. Between these rods the Mg2 atoms build chains of face-sharing trigonal prisms. Alternately these prisms are centered by Mg3 or capped by Mg1 atoms on the rectangular faces. Within the magnesium substructure the Mg-Mg distances range from 303 to 335 pm. The Mg3 site shows slight mixing with samarium, leading to the composition Sm3.16RuMg6.84 for the investigated crystal. The compounds RE3RuMg7 (RE = Gd, Tb) are isotypic.

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The Effect of the Cooling Rates on the Microstructure and High-Temperature Mechanical Properties of a Nickel-Based Single Crystal Superalloy

Materials ◽

10.3390/ma13194256 ◽

2020 ◽

Vol 13 (19) ◽

pp. 4256

Author(s):

Xiao-Yan Wang ◽

Meng Li ◽

Zhi-Xun Wen

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

Single Crystal ◽

Solution Treatment ◽

Single Crystal Superalloy ◽

Air Cooling ◽

Strengthening Effect ◽

Cooling Rates ◽

High Temperature Mechanical Properties ◽

High Temperature Tensile

The as-cast alloy of nickel-based single-crystal superalloy was used as the research object. After four hours of solution treatment at 1315 °C, four cooling rates (water cooling (WC), air cooling (AC) and furnace cooling (FC1/FC2)) were used to reduce the alloy to room temperature. Four different microstructures of nickel-based superalloy material were prepared. A high-temperature tensile test at 980 °C was carried out to study the influence of various rates on the formation of the material’s microstructure and to further obtain the influence of different microstructures on the high-temperature mechanical properties of the materials. The results show that an increase of cooling rate resulted in a larger γ′ phase nucleation rate, formation of a smaller γ′ phase and a greater number. When air cooling was used, the uniformity of the γ′ phase and the coherence relationship between the γ′ phase and the γ phase were the best. At the same time, the test alloy had the best high-temperature tensile properties, and the material showed a certain degree of plasticity. TEM test results showed that the test alloy mainly blocked dislocations from traveling in the material through the strengthening effect of γ′, and that AC had the strongest hindering effect on γ′ dislocation movement.

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New Quaternary Indides RE7Ni5–xGe3+xIn6 (RE = La, Nd, Sm)

Zeitschrift für Naturforschung B ◽

10.1515/znb-2011-0414 ◽

2011 ◽

Vol 66 (4) ◽

pp. 433-436

Author(s):

Nataliya Dominyuk ◽

Vasyl I. Zaremba ◽

Rainer Pöttgen

Keyword(s):

Single Crystal ◽

Single Crystals ◽

X Ray Diffraction ◽

Slow Cooling ◽

X Ray ◽

Arc Melting ◽

Characteristic Features

The quaternary indides RE7Ni5−xGe3+xIn6 (RE = La,Nd, Sm) were synthesized from the elements by arc-melting. Single crystals were grown by slow cooling of the polycrystalline samples. The structures were characterized by powder and single-crystal X-ray diffraction: Ce7Ni4.73Ge3.27In6 type, P6/m, Z = 1, a = 1147.05(9), c = 426.82(4) pm, wR2 = 0.0652, 528 F2 values for La7Ni4.46Ge3.54In6, a = 1134.5(7), c = 407.1(7) pm, wR2 = 0.0419, 441 F2 values for Nd7Ni4.91Ge3.09In6, and a = 1133.5(2), c = 404.3(1) pm, wR2 = 0.0619, 498 F2 values for Sm7Ni4.31Ge3.69In6, with 25 parameters per refinement. Characteristic features of the RE7Ni5−xGe3+xIn6 structures are hexagonal, AlB2-related prisms around the RE1 atoms and a tricapped, trigonalprismatic coordination of the nickel atoms

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Synthesis, crystal growth, physicochemical properties and quantum chemical investigations of a D–π–A type organic single crystal: 2-amino-5-nitropyridinium p-phenolsulfonate (2A5NPP) for nonlinear optical (NLO) applications

CrystEngComm ◽

10.1039/c7ce01202k ◽

2017 ◽

Vol 19 (37) ◽

pp. 5662-5678 ◽

Cited By ~ 22

Author(s):

V. Sivasubramani ◽

V. Mohankumar ◽

M. Senthil Pandian ◽

P. Ramasamy

Keyword(s):

Crystal Growth ◽

Physicochemical Properties ◽

Single Crystal ◽

Single Crystals ◽

Quantum Chemical ◽

Nonlinear Optical ◽

Slow Cooling ◽

Cooling Method ◽

Organic Single Crystal

Efficient organic NLO 2A5NPP single crystals have been grown by slow cooling method.

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Effects of the Mg/Si Ratio on Microstructure, Mechanical Properties, and Precipitation Behavior of Al–Mg–Si–1.0 wt %-Zn Alloys

Materials ◽

10.3390/ma11122591 ◽

2018 ◽

Vol 11 (12) ◽

pp. 2591 ◽

Cited By ~ 6

Author(s):

Yong Li ◽

Guanjun Gao ◽

Zhaodong Wang ◽

Hongshuang Di ◽

Jiadong Li ◽

...

Keyword(s):

Mechanical Properties ◽

Volume Fraction ◽

Solution Treatment ◽

Hardness Test ◽

Strengthening Effect ◽

Precipitation Behavior ◽

Scanning Calorimetry ◽

First Choice ◽

The Matrix ◽

Zn Alloys

Aluminum alloys are widely used as first-choice materials for lightweight automotive applications. It is important that an alloy have a balance between strength and formability. In this study, the alloys were melted, cast, hot rolled, and cold rolled into 1 mm-thick sheets. The microstructure, mechanical properties, and precipitation behavior of Al–Mg–Si–1.0 wt %-Zn alloys with Mg/Si ratios of 0.5, 1, and 2 after solution treatment were studied using optical and electron microscopy, a tensile test, the Vickers hardness test, and differential scanning calorimetry. The results showed that a high density and number of Al–Fe–Si particles were observed in the matrix, thus causing the formation of more homogeneous and smaller recrystallized grains after treatment with the solution. In addition, a higher volume fraction of cubeND and P-types texture components formed during solution treatment. Also, a high r value and excellent deep drawability were achieved in the medium-Mg/Si-ratio alloy. The formation of denser strengthening precipitates led to a better paint-bake hardening effect in comparison with the other two alloys. Furthermore, the precipitation kinetics were enhanced by the addition of Si, and the addition of Zn did not alter the precipitation sequence of the Al–Mg–Si alloy. The dual-phase strengthening effect was not achieved in the studied alloys during paint-bake treatment at 175 °C.

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Recycled HDPE-tetrapack composites. Isothermal crystallization, light scattering and mechanical properties

MRS Proceedings ◽

10.1557/opl.2013.252 ◽

2012 ◽

Vol 1485 ◽

pp. 77-82 ◽

Cited By ~ 2

Author(s):

A Parada-Soria ◽

HF Yao ◽

B Alvarado-Tenorio ◽

L Sanchez-Cadena ◽

A Romo-Uribe

Keyword(s):

Mechanical Properties ◽

Light Scattering ◽

Young’S Modulus ◽

Tensile Deformation ◽

Young's Modulus ◽

Ultimate Tensile Stress ◽

Uniaxial Tensile ◽

Scanning Calorimetry ◽

Slow Cooling ◽

The Matrix

ABSTRACTIn this research the thermal and mechanical properties of composites based on recycled high-density polyethylene (HDPE) and recycled Tetrapak have been investigated. The matrix and filler are recovered from landfills. Multicolor HDPE mixtures, with varying concentration of tetrapack flakes, are hot pressed, as well as single color HDPE flakes. Previous studies determine that the nature of the pigment (organics vs. inorganics) strongly influence the mechanical behavior of multicolor HDPE-tetrapack composites. Thus, this research focuses on single color HDPE hot pressed plaques. The kinetics of crystallization under isothermal conditions is determined by differential scanning calorimetry (DSC). The results show that the crystallization kinetics obeys the Avrami theory, and that the Avrami exponent is 1, irrespective of the pigment in use. Small-angle light scattering is applied to investigate the internal structure of the pigmented HDPE. SALS patterns show that the samples exhibited oriented morphologies. However, after melting and slow cooling under pressure the samples exhibit an isotropic morphology. This is confirmed by polarized optical microscopy. Mechanical properties such as Young’s modulus, yield stress and ultimate tensile stress are obtained under uniaxial tensile deformation at room temperature. For the single color HDPE plaques the Young’s modulus is reduced (after melting), suggesting that the anisotropic molecular chains contribute to the higher value of Young’s modulus.

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