A New Alloy System Having Autogenous Grain Pinning at High Temperature

Mo-Si-B alloys have been received an attention due to the high temperature strength and phase stability. However, the nature of poor oxidation resistance often limits the application of the alloy system. The unstable MoO3 phase is naturally produced when the alloys were exposed at low and /or high temperature in an air atmosphere. In order to resolve the poor oxidation resistance of the alloy system, several attempts have been made via surface coatings and/or component additions. In this study, the oxidation behaviors of the Ti powder thermal spray coated Mo-Si-B alloys have been investigated in order to identify the underlying mechanism for the effect of precursor Ti coatings on Mo-Si-B alloys. The oxidation tests performed at 1100 °C show that the Ti powder was tightly bonded and reacted with the surface of the substrate, and TiO2 layer was formed at the outer surface of the coated Ti layer as a result of oxidation exposure. The oxidation behaviors of pure elemental component coated Mo-Si-B alloys have been discussed in terms of microstructural observations during oxidation tests.

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Transformation Temperatures, Shape Memory and Magnetic Properties of Hafnium Modified Ti-Ta Based High Temperature Shape Memory Alloys

High Temperature Materials and Processes ◽

10.1515/htmp-2015-0113 ◽

2017 ◽

Vol 36 (2) ◽

pp. 113-119

Author(s):

W.Q. Khan ◽

Q. Wang ◽

X. Jin

Keyword(s):

High Temperature ◽

Shape Memory ◽

Alloy System ◽

Heat Of Reaction ◽

Transformation Temperatures ◽

Dsc Measurements ◽

Recovery Strain ◽

Shape Memory Properties ◽

Three Point Bend Test ◽

Point Bend

AbstractIn this study the modification effect of Hf content on the shape memory properties and magnetic permeability of a 75.5-77Ti-20Ta-3-4.5Hf alloy system has been systematically studied by DSC, three-point bend test, vector network analyzer and XRD. The martensitic transformation temperature, heat of reaction and recovery strain increases with the increase of hafnium and tantalum content. A stable high temperature shape memory effect was observed (Ms = 385–390 °C) during the two thermal cycles between 20 °C and 725 °C. Transformation temperatures and heats of reaction were determined by DSC measurements. Recovery strain was determined by three-point bend testing. Also an alloy, 70Ti-26Ta-4Hf, with higher tantalum content was produced to observe the effect of Ta on the shape memory properties. Permeability increases gradually from 1.671 to 1.919 with increasing content of hafnium modification and remains stable in the frequency range of 450 MHz to 1 GHz.

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Microstructure Analysis of The Channel Regions in Dual Two-phase Intermetallic Alloy Based on The Ni3Al-Ni3V Pseudo-binary Alloy System

MRS Proceedings ◽

10.1557/opl.2011.370 ◽

2011 ◽

Vol 1295 ◽

Author(s):

T. Moronaga ◽

Y. Kaneno ◽

H. Tsuda ◽

T. Takasugi

Keyword(s):

High Temperature ◽

Binary Alloy ◽

Lattice Misfit ◽

Alloy System ◽

Dark Field ◽

Intermetallic Alloys ◽

Two Phase ◽

Transmission Electron ◽

Phase Intermetallic ◽

Binary Alloy System

ABSTRACTDual two-phase intermetallic alloys based on the Ni3Al-Ni3V pseudo-binary alloy system have been reported to display high phase and microstructure stabilities and good mechanical properties at high temperature and are therefore considered to be used as a next generation type of high temperature structural materials. The microstructure of the dual two-phase intermetallic alloys is composed of primary Ni3Al and the channel (eutectoid) regions consisting of Ni3Al+Ni3V. In this study, the microstructure of the channel regions was investigated by a transmission electron microscope (TEM). The contrasts of the channel regions showed a complicated microstructure in bright-field images. However, the electron beam diffraction consisted of a single set of patterns and the spots did not accompany streaks, indicating that crystallographic coherency among the constituent phases or the domains is very high. It was also shown that the lattice misfit between the a-axis of Ni3Al and the c-axis of Ni3V is larger than that between the a-axis of Ni3Al and the a-axis of Ni3V. From the dark-field observation, it was found that the c-axis of Ni3V domains in the channel regions is oriented perpendicular to the interface between primary Ni3Al and Ni3V. Therefore, it is suggested that the crystallographic orientation of Ni3V in the channel regions is aligned in the manner of lowering an internal stress caused by the lattice misfit between primary Ni3Al precipitates and Ni3V domains.

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THE MECHANISM OF THE FORMATION OF CRACKS IN THE LASER-DEPOSITED NICKEL ALLOY SYSTEM NI–CR–B–SI ON THE SURFACE OF STRUCTURAL STEEL TYPE 30CGSA

Spravochnik Inzhenernyi zhurnal ◽

10.14489/hb.2020.01.pp.003-010 ◽

2020 ◽

pp. 3-10

Author(s):

V. P. Morozov ◽

Yu. G. Romanov

Keyword(s):

High Temperature ◽

Crack Formation ◽

Alloy System ◽

Powder Materials ◽

High Temperature Region ◽

Second Stage ◽

Stage Of Development ◽

Small Cracks ◽

Formation Of Cracks ◽

Technological Strength

The mechanism of crack formation in the deposited layers is investigated. In accordance with this mechanism, cracks are of the nature of “hot” cracks. The reasons that enhance crack formation during surfacing of powder materials of the Ni–Cr–B–Si system are examined and identified. Foci of “hot” small cracks are formed, as a rule, in the high-temperature region. At the second stage, the focus develops, developing into transcrystalline destruction. The second stage of development is associated with the process of accumulation of internal welding stresses in the area of the source. The main parameters that determine the technological strength of the metal during surfacing or welding are: the length of the temperature range of brittleness (TIC), the level of ductility of the metal in the TIC and the intensity of the shrinkage deformation of the metal in the TIC. It was established that it is possible to increase the service life of the restored product several times in comparison with the new part by eliminating cracks in the deposited layer.

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Oxidation Behaviors of Two and Three Phase Mo-Si-B Alloys via Si Pack Cementation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.2446 ◽

2012 ◽

Vol 706-709 ◽

pp. 2446-2449

Author(s):

Young Ho Song ◽

Joon Sik Park ◽

Jeong Min Kim ◽

Seong Hoon Yi

Keyword(s):

High Temperature ◽

Oxidation Resistance ◽

Alloy System ◽

Underlying Mechanism ◽

High Temperature Strength ◽

Three Phase ◽

Phase Combination ◽

Temperature Exposure ◽

Poor Oxidation Resistance ◽

Oxidation Behaviors

Mo-Si-B alloys have been received an attention due to the high temperature strength and phase stability. However, the nature of poor oxidation resistance often limits the application of the alloy system. In order to resolve the poor oxidation resistance of the alloy system, in this study, the oxidation behaviors of Si diffusion coated Mo-Si-B alloys have been investigated in order to identify the underlying mechanism for the effect of the constituent of the phase combination of Mo-Si-B alloys. The oxidation tests performed at 1100 °C show that the produced MoSi2 phase, as a result of the coatings, give an excellent oxidation resistance at prolonged high temperature exposure in air. The oxidation behaviors of uncoated and Si coated Mo-Si-B alloys have been discussed in terms of microstructural observations during oxidation tests.

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Microstructure and Mechanical Properties of Dual Two-Phase Intermetallic Alloys Composed of GCP Ni3Al and Ni3V Phases containing Nb

MRS Proceedings ◽

10.1557/proc-980-0980-ii05-27 ◽

2006 ◽

Vol 980 ◽

Author(s):

Wataru Soga ◽

Yasuyuki Kaneno ◽

Takayuki Takasugi

Keyword(s):

High Temperature ◽

Creep Test ◽

Alloy System ◽

High Yield ◽

Intermetallic Alloys ◽

Two Phase ◽

Electron Microscopies ◽

Compression Creep ◽

Phase Intermetallic ◽

Multi Phase

AbstractDual multi-phase intermetallic alloys composed of Ni3X (X: Al and V) containing Nb were developed, on the basis of the Ni3Al-Ni3Nb-Ni3V pseudo-ternary alloy system. The dual multi-phase intermetallic alloys were characterized by scanning electron and transmission electron microscopies. High-temperature compression and tension tests, and compression creep test were conducted. It was found that the dual multi-phase intermetallic alloys show high yield and tensile strength with good temperature retention, accompanied with reasonable tensile ductility. The compression creep test conducted at high temperature showed lower creep rate in the dual multi-phase intermetallic alloys than in conventional Ni-base superalloys. The obtained results are superior to the dual multi-phase intermetallic alloys containing Ti.

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A Review of TiNiPdCu Alloy System for High Temperature Shape Memory Applications

Shape Memory and Superelasticity ◽

10.1007/s40830-015-0019-y ◽

2015 ◽

Vol 1 (2) ◽

pp. 85-106 ◽

Cited By ~ 3

Author(s):

M. Imran Khan ◽

Hee Young Kim ◽

Shuichi Miyazaki

Keyword(s):

High Temperature ◽

Shape Memory ◽

Alloy System ◽

Memory Applications

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Creep Damage Mechanisms in Cast Cobalt Superalloys for Applications in Glass Industry

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.774.173 ◽

2018 ◽

Vol 774 ◽

pp. 173-178

Author(s):

Marie Kvapilová ◽

Božena Podhorná ◽

Jiri Dvorak ◽

Petr Král ◽

Jiří Zýka ◽

...

Keyword(s):

High Temperature ◽

Critical Role ◽

Creep Damage ◽

Alloy System ◽

High Temperature Creep ◽

Precision Casting ◽

Temperature Creep ◽

Complex Carbides ◽

The Matrix ◽

Damage Processes

Two cast NbC and TaC- strengthened cobalt-base superalloys have been developed for a precision casting of spinner discs for glass wool industry. In the present study, the relationships between the type and morphology of carbides and the degradation processes in both types of cast cobalt-based superalloys subjected to high temperature creep have been examined. It was found that the nature of carbides within the alloy microstructure plays a critical role in determining the creep damage processes and microstructure stability of the alloy system under high temperature creep. The morphology of the carbides is a strong function of their chemical composition. The interface decohesion between the complex carbides and the matrix and cracking of the brittle carbides homogeneously distributed in the crept NbC - strengthened alloy lead to brittle intergranular and/or interdendritic fracture. By contrast, Ta - strengthened alloy exhibited very small extent of isolated creep damage and the final fracture is ductile transgranular mode.

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Complex Intermetallics in the Al-Rich Part of Al-Pd-Cr System

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.163.272 ◽

2010 ◽

Vol 163 ◽

pp. 272-277

Author(s):

W. Kowalski ◽

B. Grushko ◽

Włodzimierz Bogdanowicz ◽

M. Surowiec

Keyword(s):

High Temperature ◽

Ternary Phase ◽

Phase 1 ◽

Orthorhombic Phase ◽

Alloy System ◽

Hexagonal Structure ◽

Lattice Parameters ◽

Orthorhombic Structure ◽

Compositional Range ◽

Cr System

The Al-Pd-Cr alloy system was investigated at 680 to 990°C in the compositional range above 60 at.% Al. The binary Al-Cr , μ and phases dissolves up to 1 at.% of Al, the η-phase extends up to 2 at.% of Pd and the 2-phase extends up to 3 at.% of Pd, respectively. The binary Al-Pd -phases dissolves up to 3 at.% of Cr and -phase up to 4 at.% Cr. Close to the high-Pd limit of the -range a ternary phase is formed between about Al78Pd4Cr18, Al77Pd10Cr13 and Al74Pd7Cr19. Its structure is orthorhombic with lattice parameters: a = 1.47, b = 1.24 and c = 1.25 nm, resembling the lattice parameters of the high-temperature Al3Mn phase. A hexagonal structure with a = 1.77 and c = 1.25 nm resembling Al-Ni(Cu)-Cr ζ-phase [1-3] was revealed around Al81.5Pd1.5Cr27 and another hexagonal structure with very close lattice parameters around Al73Pd11Cr16. Another ternary phase was found in 970°C around the Al77.5Pd1.5Cr21 composition. It has orthorhombic structure with a = 1.24, b = 3.46 and c = 2.04 nm resembling the ternary -phase in Al-Ni-Cr. An additional orthorhombic phase with a = 2.48, b= 3.87 and c = 2.04 nm was found to be formed between about Al82Pd4Cr14, Al79Pd4Cr17 and Al79Pd9Cr12.

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