scholarly journals Prediction of superconductivity in pressure-induced new silicon boride phases

2020 ◽  
Vol 101 (1) ◽  
Author(s):  
Xiaowei Liang ◽  
Aitor Bergara ◽  
Yu Xie ◽  
Linyan Wang ◽  
Rongxin Sun ◽  
...  
Keyword(s):  
Boride Phases

scholarly journals Effect of In-Situ Synthesized Boride Phases on the Impact Behavior of Iron-Based Composites Reinforced by B4C Particles

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 554
Author(s):  
Fehmi Nair ◽  
Mustafa Hamamcı
Keyword(s):  
Contact Forces ◽  
Impact Behavior ◽  
Iron Matrix ◽  
Impact Tests ◽  
B4c Particles ◽  
Iron Based ◽  
In Situ Reactions ◽  
Boride Phases ◽  
The Impact

The objective of this study is to investigate the impact behavior of iron-based composites reinforced with boron carbide (B4C) particles and in-situ synthesized iron borides (Fe2B/FeB). The composite specimens (Fe/B4C) were fabricated by hot-pressing under a pressure of 250 MPa at 500 °C, and sintered at a temperature of 1000 °C. The effects of the reinforcement ratio on the formation of in-situ borides and impact behavior were investigated by means of different volume fractions of B4C inside the iron matrix: 0% (un-reinforced), 5%, 10%, 20%, and 30%. Drop-weight impact tests were performed by an instrumented Charpy impactor on reinforced and un-reinforced test specimens. The results of the impact tests were supported with microstructural and fractographical analysis. As a result of in-situ reactions between the Fe matrix and B4C particles, Fe2B phases were formed in the iron matrix. The iron borides, formed in the iron matrix during sintering, heavily affected the hardness and the morphology of the fractured surface. Due to the high amount of B4C (over 10%), porosity played a major role in decreasing the contact forces and fracture energy. The results showed that the in-situ synthesized iron boride phases affect the impact properties of the Fe/B4C composites.

scholarly journals The Microstructure, Mechanical Properties and Coatability of Diffusion Brazed CMSX-4 Single Crystal

1996 ◽  
Author(s):  
Warren M. Miglietti ◽  
Ros C. Pennefather
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Elevated Temperatures ◽  
Aluminide Coating ◽  
Turbine Blades ◽  
Stress Rupture ◽  
Directionally Solidified ◽  
Diffusion Brazing ◽  
Brazed Joints ◽  
Boride Phases

Diffusion brazing is a joining process utilized both in the manufacture and repair of turbine blades and vanes. CMSX-4 is an investment cast, single crystal, Ni-based superalloy used for turbine blading and vanes, and has enhanced mechanical properties at elevated temperatures when compared to equiaxed, directionally solidified and first generation single crystal superalloys. The objective of this work was to develop a diffusion brazing procedure to achieve reliable joints in the manufacture of a hollow turbine blade (for a prototype engine in South Africa), and to verify the coatability of the diffusion brazed joints. Two commercially available brazing filler metals of composition Ni-15Cr-3.5B and Ni-7Cr-3Fe-4.5Si-3.2B-0.06C and a proprietary (wide gap) braze were utilized. With the aim of eliminating brittle centre-line boride phases, the effects of temperature and time on the joint microstructure were studied. Once the metallurgy of the joint was understood, tensile and stress rupture tests were undertaken, the latter being one of the severest tests to evaluate joint strength. The results demonstrated that the diffusion brazed joints could satisfy the specified stress rupture criterion of a minimum of 40 hrs life at 925 °C and 200 MPa. After mechanical property evaluations, an investigation into the effects of a low temperature high activity (LTHA) pack aluminide coating and a high temperature low activity (HTLA) pack aluminide coating on the braze joints was undertaken. The results showed that diffusion brazed joints could be readily coated.

Diffusion formation of boride phases on the iron surface

2010 ◽  
Vol 36 (3) ◽  
pp. 382-387 ◽  
Author(s):  
S. I. Sviridov ◽  
Z. G. Tyurnina ◽  
N. G. Tyurnina
Keyword(s):  
Iron Surface ◽  
Boride Phases

Synthesis, Crystal Chemistry and Magnetism of the Metal-rich Borides MxRh7–xB3 (M = Cr, Mn, Ni; x = 0.39–1) with Th7Fe3-type Structure

2011 ◽  
Vol 66 (12) ◽  
pp. 1241-1247
Author(s):  
Patrick R.N. Misse ◽  
Richard Dronskowski ◽  
Boniface P. T. Fokwa
Keyword(s):  
Melting Furnace ◽  
Structure Type ◽  
Argon Atmosphere ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Arc Melting ◽  
Pauli Paramagnetism ◽  
Powder Samples ◽  
Boride Phases

Powder samples and single crystals of the boride phases MxRh7−xB3 (M = Cr,Mn, Ni; x ≤ 1) have been synthesized from the elements using an arc-melting furnace under purified argon atmosphere in a water-cooled copper crucible. The new phases were characterized from single-crystal and powder X-ray diffraction, as well as semi-quantitative EDX measurements. The obtained phases crystallize in the hexagonal Th7Fe3 structure type (space group P63mc, no. 186, Z = 2). In all cases (M = Cr, Mn, Ni), M is found to preferentially mix with rhodium at only one (6c) of the three available rhodium positions. Pauli paramagnetism was observed in CrxRh7−xB3 (x < 1), whereas both Pauli and temperature-dependent paramagnetisms were found in NiRh6B3.

The effect of rapid solidification by spinning and laser melting On the structure of sendust-type alloys

1994 ◽  
Vol 362 ◽  
Author(s):  
Elena N. Sheftel ◽  
Dmitry E. Kaputkin ◽  
Raissa E. Stroug
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Wear Resistance ◽  
Rapid Solidification ◽  
Magnetic Alloy ◽  
Dispersion Strengthening ◽  
Soft Magnetic ◽  
Laser Melting ◽  
Soft Magnetic Alloy ◽  
Boride Phases

AbstractDispersion strengthening of the most wear-resistant soft magnetic alloy Sendust (Fe-9.5 wt.%Si -5.5 wt.% Al, HV=5000 MPa) by carbide and boride phases allowed to increase its wear-resistance by a factor of 2 to 3. Hardness of the dispersion strengthened alloys is HV=5500–6250 MPa. The changes in grain size, ordering and hardness of the Sendust and two dispersion strengthened alloys have been studied after spinning and various regimes of laser melting. Both types of rapid solidification caused a significant decrease of both the solid solution grain size and the size of carbide and boride phases. While spinning only significantly decreased the amount of ordered Fe3(Si,Al) phase in all the alloys, laser melting completely suppressed the ordering. The hardness of the boride strengthened alloy increased up to 7550 MPa after laser melting.

Effect of Ruthenium, Rhenium and Yttria Additions on the Microstructure of Wide Gap Brazing of IN738

2007 ◽  
Author(s):  
Xiao Huang ◽  
Scott Yandt ◽  
Doug Nagy ◽  
Matthew Yao
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Life Cycle Cost ◽  
Filler Metal ◽  
Braze Alloy ◽  
Cost Effective ◽  
Brazed Joints ◽  
Brazed Joint ◽  
Wide Gap ◽  
Boride Phases

Modern gas and steam turbine components are subject to severe thermomechanical loads and extremely high temperature in order to provide increased performance and efficiency. Most high temperature turbine components are made of superalloys specifically developed for high temperature and high mechanical stress applications but at considerable cost. Defects may occur during manufacturing of superalloy castings as well as after service. Repair of these components, rather than replacement, helps to reduce the life cycle cost. Wide gap brazing is a cost effective and reliable means to repair gas turbine hot section components with defect sizes exceeding 0.3 mm. With proper control of the braze alloy and brazing cycle, the repaired region has been reported to posses mechanical properties approaching that of the parent materials. In order to further improve the mechanical properties of the repaired region and to explore the possibility of employing the wide gap brazing method to repair single crystal components in the future, three alloying additions, Ruthenium (Ru), Rhenium (Re) and yttria (Y2O3), were incorporated into the braze filler metal by mechanical alloying. The microstructures of the wide gap brazed joints with Ru, Re and yttria additions were studied and compared to a braze joint with standard wide gap braze alloys of IN738 and AWS BNi-9. It has been found that two types of borides formed in all braze alloys, namely eutectic γ-Ni-rich and boride phases and discrete boride containing primarily Cr and W (or Ru). The addition of Ru to the filler metal did not seem to modify the microstructural constituents after brazing. However, Ru partitioned strongly to the discrete borides. No isolated elemental Ru region was observed. On the other hand, Re addition was found to change the occurrence and distribution of both types of borides. The eutectic boride constituent was significantly reduced and finer discrete boride particles were observed. The addition of yttria did not change the boride formation but led to the generation of more voids in the brazed joint.

Complex metallophysical studies of structural steels after two-component diffusion hardening based on boron

2021 ◽  
pp. 18-24
Author(s):  
V.M. Roshchupkin ◽  
Yu.V. Skripkina ◽  
V.N. Gadalov ◽  
O.M. Gubanov
Keyword(s):  
Brittle Failure ◽  
Structural Steels ◽  
Dynamic Effects ◽  
English Version ◽  
Surface Layers ◽  
Powder Mixtures ◽  
Wear Process ◽  
Two Component ◽  
Structure Phase ◽  
Boride Phases

The studies of the structure, phase composition and microhardness of 45; 40X13 and (25...30) CMT steels during hardening in mixtures containing boron, boron and silicon, as well as boron, silicon and aluminum, are presented. Boration was carried out at a temperature of 890°C for 3 hours. The results of the study show that as a result of boration, the layer thickness is greater than in the case of borosiliconizing and boro-alumino-siliconizing, however, the needles of the boride phases are sharper. By obtaining diffusive layers that differ in structure with different phase ratios FeB, Fe2 B, Fe3 Si, it is possible to significantly influence the resistance to brittle failure of the surface layers of parts that are operated under real conditions in friction pairs under periodic or constant shock effects. So, if the wear process proceeds without ever manifesting dynamic effects, then it is possible to recommend the use of the boration process – both for small-sized parts with CTR in powder mixtures using unpressurized containers, and large-sized parts - in coatings that are applied only to the wearing surfaces of the parts. If the wear occurs under conditions of a relatively low level of periodically manifested shock effects, it is possible to use the borosiliconizing process at (800...900)°C. English version of the article is available at URL: https://panor.ru/articles/complex-metal-physical-studies-of-structural-steels-after-twocomponent-boron-based-diffusion-hardening/69778.html

New Powdered Silicide Materials for Thermal Spraying Process and Coatings on the Niobium Base Alloys

1998 ◽  
Author(s):  
V. Terentieva ◽  
O. Bogatchkova ◽  
D. Cornu
Keyword(s):  
Protective Coating ◽  
Protective Coatings ◽  
Thermal Spraying ◽  
Base Material ◽  
Theory And Practice ◽  
Powder Materials ◽  
Self Healing ◽  
High Enthalpy ◽  
Boride Phases ◽  
Spraying Process

Abstract The given article presents some results of the scientific research devoted to the development of a new class of scale-resistant powder materials of the Si-Ti-Mo-B system for thermal spraying and using these materials for the creation of heat-resistant coatings on the niobium base alloys by means of various methods of thermal spraying. Also under consideration are problems relating to the theory and practice of obtaining reliable protective coatings on high-melting metals and their alloys, niobium ones included, intended for operation in high-enthalpy oxygen-containing gas flows. Hazard in commencing an oxidation reaction of the base material under coating is connected with density of open pores and cracks, and partial pressure of the oxidizer. Powdered multicomponent heterophase materials for gas-thermal spraying of protective coating with a self-healing ability and controlled properties are proposed. Finally the results of some properties of new silicide-type heterophase powders containing silicide and boride phases for a thermal spraying process and some properties of protective coating deposited on the niobium base alloys by means of a thermal spraying technique are presented.

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