scholarly journals Coating Reactions on Vanadium and V-Si-B Alloys during Powder Pack-Cementation

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4099
Author(s):  
Georg Hasemann ◽  
Chad Harris ◽  
Manja Krüger ◽  
John H. Perepezko
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
Refractory Metal ◽  
Pack Cementation ◽  
Solid Solution Phase ◽  
Major Drawback ◽  
Three Phase ◽  
Structural Applications ◽  
New Type ◽  
Refractory Metal Alloys

Alloys in the V-Si-B system are a new and promising class of light-weight refractory metal materials for high temperature applications. Presently, the main attention is focused on three-phase alloy compositions that consist of a vanadium solid solution phase and the two intermetallic phases V3Si and V5SiB2. Similar to other refractory metal alloys, a major drawback is the poor oxidation resistance. In this study, initial pack-cementation experiments were performed on commercially available pure vanadium and a three-phase alloy V-9Si-5B to achieve an oxidation protection for this new type of high temperature material. This advance in oxidation resistance now enables the attractive mechanical properties of V-Si-B alloys to be used for high temperature structural applications.

Phase transformation and layer evolution in molybdenum disilicide-silicon carbide nanolayered coatings

1994 ◽  
Vol 52 ◽  
pp. 538-539
Author(s):  
H. Kung ◽  
T. R. Jervis ◽  
J.-P. Hirvonen ◽  
M. Nastasi ◽  
T. E. Mitchell ◽  
...  
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Oxidation Resistance ◽  
Elevated Temperatures ◽  
Matrix Material ◽  
Molybdenum Disilicide ◽  
High Temperature Strength ◽  
Cross Sectional ◽  
Good Oxidation Resistance ◽  
Structural Applications

MoSi2 is a potential matrix material for high temperature structural composites due to its high melting temperature and good oxidation resistance at elevated temperatures. The two major drawbacksfor structural applications are inadequate high temperature strength and poor low temperature ductility. The search for appropriate composite additions has been the focus of extensive investigations in recent years. The addition of SiC in a nanolayered configuration was shown to exhibit superior oxidation resistance and significant hardness increase through annealing at 500°C. One potential application of MoSi2- SiC multilayers is for high temperature coatings, where structural stability ofthe layering is of major concern. In this study, we have systematically investigated both the evolution of phases and the stability of layers by varying the heat treating conditions.Alternating layers of MoSi2 and SiC were synthesized by DC-magnetron and rf-diode sputtering respectively. Cross-sectional transmission electron microscopy (XTEM) was used to examine three distinct reactions in the specimens when exposed to different annealing conditions: crystallization and phase transformation of MoSi2, crystallization of SiC, and spheroidization of the layer structures.

Pest Resistant and Low CTE MoSi2-Matrix for High Temperature Structural Applications

1994 ◽  
Vol 350 ◽  
Author(s):  
M. G. Hebsur
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Matrix Composition ◽  
Temperature Oxidation ◽  
Accelerated Oxidation ◽  
Structural Applications ◽  
Base Matrix ◽  
Sic Reinforcement

AbstractThe objective of this investigation was to identify a pest resistant MoSi2-base matrix composition having properties suitable for SiC reinforcement. A 30 vol.% addition of fine Si3N4 particulates to MoSi2 significantly improved the low temperature accelerated oxidation resistance and thereby eliminated pest failure. Addition of Si3N4 also improved the high temperature oxidation resistance, strength and more importantly lowered the CTE of MoSi2 such that cracking was eliminated in a hybrid composite consisting of 30 vol.% Si3N4 and 30 vol. % SCS-6 fibers.

HAYNES NS-163 Alloy: A Novel Nitride Dispersion-Strengthened CO-Base Alloy

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Michael G. Fahrmann ◽  
Vinay P. Deodeshmukh ◽  
S. Krishna Srivastava
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Oxidation Resistance ◽  
Base Alloy ◽  
Nitriding Process ◽  
Dispersion Strengthening ◽  
Annealed Condition ◽  
Gas Nitriding ◽  
Diffusion Controlled ◽  
Structural Applications

HAYNES® NS-163® alloy was developed by Haynes International Inc., Kokomo, IN, for high-temperature structural applications by pursuing a dual manufacturing approach: the fabrication of components in the readily weldable and formable mill-annealed condition, and their subsequent strengthening by means of a gas nitriding process. The latter process results in dispersion-strengthening by virtue of formation of internal nitrides. Since this process is diffusion-controlled, component section thicknesses are limited to approximately 2.0 mm (0.080 in.). Microstructures and mechanical properties of nitrided sheet samples are presented. Oxidation resistance and the need for coatings at temperatures exceeding 980 °C (1800 °F) are addressed as well.

The Investigation of the Interdiffusion Barrier in TiAl/MCrAlY System

2010 ◽  
Vol 654-656 ◽  
pp. 1920-1923 ◽  
Author(s):  
Wen Wang ◽  
Yu Xian Cheng ◽  
Sheng Long Zhu ◽  
Fu Hui Wang ◽  
Li Xin
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
Diffusion Barrier ◽  
High Temperature Oxidation ◽  
Temperature Oxidation ◽  
The Poor ◽  
Structural Applications ◽  
Nicraly Coating ◽  
Overlay Coatings ◽  
Poor Oxidation Resistance

TiAl based alloys are promising candidates for structural applications at high temperature. However, the poor oxidation resistance above 800oC obviously restrains their applications. Although NiCrAlY overlay coatings can remarkably improve the high temperature oxidation resistance of TiAl, serious inward diffusion of Ni from the coating to the substrate occurs which could reduce the lifetime of the coating/substrate system. Apparently, the development of interdiffusion barrier could overcome the disadvantage of the NiCrAlY/TiAl system. In this work, Ta, TiN and Cr2O3 interlayers were deposited between NiCrAlY coating and γ-TiAl substrate as diffusion barrier (DB). The interdiffusion behavior of the TiAl/DB/NiCrAlY system was investigated at 1000°C. The results showed that the metallic and nitride interlayers cannot retard the interdiffusion of Ni effectively. As an active diffusion barrier, the oxide interlayer obviously suppressed the inward diffusion of Ni from the coating to the substrate by the formation of alumina-rich layers at both the TiAl/DB and DB/NiCrAlY interfaces.

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

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.

High Temperature Mechanical Behavior of a Mo-Si-B Solid Solution Alloy

2006 ◽  
Vol 980 ◽  
Author(s):  
Padam Jain ◽  
K. S. Kumar
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Mechanical Response ◽  
Tensile Tests ◽  
Solid Solution Alloy ◽  
Solid Solution Phase ◽  
Nominal Strain Rate ◽  
Three Phase ◽  
The Matrix ◽  
Multi Phase

AbstractMulti phase alloys at the Mo-rich end of the Mo-Si-B system have drawn recent attention because of their high temperature performance capabilities. Previous studies on two- and three-phase alloys have confirmed the central role of the Mo-rich solid solution phase in affecting creep resistance and low-temperature toughness in these multiphase alloys. Thus, it is important to understand the intrinsic mechanical response of the matrix solid solution. In this study, compression and tensile tests were conducted over a nominal strain rate regime spanning 10-4 s-1 to 10-7 s-1 and temperature ranging from 1000°C to 1300°C in vacuum on a Mo-Si-B solid solution alloy (Mo-3Si-1.3B in at.%) that contained a low fraction (~5 %) of the T2 phase. The microstructure of the deformed specimens was examined to elucidate the underlying deformation mechanisms.

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