scholarly journals Wide-Gap Brazing of K417G Alloy Assisted by In Situ Precipitation of M3B2 Boride Particles

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3140 ◽  
Author(s):  
Zhun Cheng ◽  
Xiaoqiang Li ◽  
Minai Zhang ◽  
Shengguan Qu ◽  
Huiyun Li
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Room Temperature ◽  
Distribution Characteristics ◽  
Powder Metallurgy Technique ◽  
Dispersion Strengthening ◽  
Eutectic Transformation ◽  
Wide Gap ◽  
Strength And Plasticity

In this study, K417G Ni-based superalloy with a 20-mm gap was successfully bonded at 1200 °C using powder metallurgy with a powder mixture. The results indicated that the microstructure and mechanical properties of the as-bonded alloy were highly dependent on the brazing time (15–45 min), mainly due to the precipitation and distribution characteristics of M3B2 boride particles. Specifically, alloy brazed for 30 min exhibited desirable mechanical properties, such as a high tensile ultimate strength of 971 MPa and an elongation at fracture of 6.5% at room temperature, exceeding the balance value (935 MPa) of the base metal. The excellent strength and plasticity were mainly due to coherent strengthening and dispersion strengthening of the in situ spherical and equiaxed M3B2 boride particles in the γ + γ′ matrix. In addition, the disappearance of dendrites and the homogenization of the microstructure are other factors that cannot be excluded. This powder metallurgy technique, which can avoid the eutectic transformation of traditional brazing, provides a new effective method for wide-gap repair of alloy materials.

Un-Bundled Carbon Nanotubes Reinforced Light Metal Composites via Powder Metallurgy Route

2011 ◽  
Vol 690 ◽  
pp. 339-342
Author(s):  
Katsuyoshi Kondoh ◽  
Thotsaphon Threrujirapapong ◽  
Hiroyuki Fukuda ◽  
Junko Umeda
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Tensile Strength ◽  
Powder Metallurgy ◽  
Pure Titanium ◽  
Hot Extrusion ◽  
Light Metal ◽  
Dispersion Strengthening ◽  
Multi Wall Carbon Nanotubes

By using light metal (Mg, Al, Ti) powders coated with un-bundled multi-wall carbon nanotubes (MWCNTs) via wet process, powder metallurgy (P/M) light metal matrix composite reinforced with un-bundled nanotubes was prepared by spark plasma sintering (SPS) and subsequently hot extrusion process. The microstructure and mechanical properties of the composites were evaluated. In the case of pure titanium, the distribution of CNTs and in-situ formed titanium carbide (TiC) compounds during sintering was investigated by optical and scanning electron microscopy (SEM) equipped with EDS analyzer. The mechanical properties of TMC were significantly improved by the additive of CNTs. For example, when employing the pure titanium composite powder coated with CNTs of 0.35 mass%, the increase of tensile strength and yield stress of the extruded TMC was 157 MPa and 169 MPa, respectively, compared to those of extruded titanium materials with no CNT additive. Fractured surfaces of tensile specimens were analyzed by SEM, and the uniform distribution of CNTs and TiC particles, being effective for the dispersion strengthening, at the surface of the TMC were obviously observed. In the case of Mg-Al alloys, in-situ formation of Al2MgC2compounds at the interface between CNTs and Mg-matrix occurred and effective for the tensile transfer loading, and resulted in the increment of tensile strength of the composite material.

scholarly journals Role of carbon and nitrogen in the improvement of corrosion resistance of new powder metallurgy Co-Cr-Mo alloys

2020 ◽  
Vol 38 (3) ◽  
pp. 273-286 ◽  
Author(s):  
Cristina Garcia-Cabezon ◽  
Celia Garcia-Hernandez ◽  
Maria L. Rodriguez-Mendez ◽  
Gemma Herranz ◽  
Fernando Martin-Pedrosa
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Powder Metallurgy ◽  
Nitrogen Content ◽  
Powder Metallurgy Technique ◽  
Carbon And Nitrogen ◽  
Physiological Conditions ◽  
Carbon And Nitrogen Content ◽  
Astm F75

AbstractMicrostructural changes that result in relevant improvements in mechanical properties and electrochemical behavior can be induced using different sintering conditions of ASTM F75 cobalt alloys during their processing using powder metallurgy technique. It has been observed that the increase in carbon and nitrogen content improves corrosion resistance and mechanical properties as long as the precipitation of carbides and nitrides is avoided, thanks to the use of rapid cooling in water after the sintering stage. In addition, the reduction of the particle size of the powder improves hardness and resistance to corrosion in both acid medium with chlorides and phosphate-buffered medium that simulates the physiological conditions for its use as a biomaterial. These results lead to increased knowledge of the role of carbon and nitrogen content in the behavior displayed by the different alloys studied.

Mechanical properties of NiAl-Mo composites produced by specially controlled directional solidification

2012 ◽  
Vol 1516 ◽  
pp. 255-260 ◽  
Author(s):  
G. Zhang ◽  
L. Hu ◽  
W. Hu ◽  
G. Gottstein ◽  
S. Bogner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Directional Solidification ◽  
Creep Resistance ◽  
Room Temperature ◽  
Growth Direction ◽  
Nominal Composition ◽  
Potential Candidate ◽  
In Situ Composites

ABSTRACTMo fiber reinforced NiAl in-situ composites with a nominal composition Ni-43.8Al-9.5Mo (at.%) were produced by specially controlled directional solidification (DS) using a laboratory-scale Bridgman furnace equipped with a liquid metal cooling (LMC) device. In these composites, single crystalline Mo fibers were precipitated out through eutectic reaction and aligned parallel to the growth direction of the ingot. Mechanical properties, i.e. the creep resistance at high temperatures (HT, between 900 °C and 1200 °C) and the fracture toughness at room temperature (RT) of in-situ NiAl-Mo composites, were characterized by tensile creep (along the growth direction) and flexure (four-point bending, vertical to the growth direction) tests, respectively. In the current study, a steady creep rate of 10-6s-1 at 1100 °C under an initial applied tensile stress of 150MPa was measured. The flexure tests sustained a fracture toughness of 14.5 MPa·m1/2at room temperature. Compared to binary NiAl and other NiAl alloys, these properties showed a remarkably improvement in creep resistance at HT and fracture toughness at RT that makes this composite a potential candidate material for structural application at the temperatures above 1000 °C. The mechanisms responsible for the improvement of the mechanical properties in NiAl-Mo in-situ composites were discussed based on the investigation results.

Microstructure and Mechanical Properties of the Wide-Gap Region Brazed with Various Powder Mixing Ratios of Additive to Filler Metal Powders

2006 ◽  
Vol 118 ◽  
pp. 479-484 ◽  
Author(s):  
Yong Hwan Kim ◽  
S.I. Kwun
Keyword(s):  
Mechanical Properties ◽  
Metal Powder ◽  
Room Temperature ◽  
Filler Metal ◽  
Metal Powders ◽  
Powder Mixing ◽  
Factors Affecting ◽  
Mixing Ratios ◽  
Microstructure And Mechanical Properties ◽  
Wide Gap

This study investigated the microstructure and mechanical properties of the wide-gap region brazed with various powder mixing ratios of additive powder (IN738) to filler metal powder (DF4B). The wide-gap brazing process was carried out in a vacuum of 2×10-5 torr at 1230°C for 1 hr. The microstructure of the brazed region was analyzed by FESEM and AES. The wide-gap region brazed with 60wt.% IN738 additive powder and 40 wt.% DF 4B filler metal powder had a microstructure consisting of Ni solid solution + γ' and (Cr, W)2B. The fracture strength of the wide-gap region brazed with 60 wt.% IN738 additive and 40 wt.% DF 4B powder was as high as 832 MPa at room temperature. It was found that the (Cr, W)2B and pores in the brazed region are important microstructural factors affecting the mechanical properties of the wide-gap brazed region.

scholarly journals Mechanical Properties of In-Situ Synthesis of Ti-Ti3Al Metal Composite Prepared by Selective Laser Melting

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1121 ◽  
Author(s):  
Li ◽  
Liang ◽  
Tian ◽  
Yang ◽  
Xie ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Selective Laser Melting ◽  
Melting Process ◽  
In Situ Synthesis ◽  
Metal Composite ◽  
Dispersion Strengthening ◽  
Laser Melting ◽  
Compression Properties

Titanium composite strengthened by Ti3Al precipitations is considered to be one of the excellent materials that is widely used in engineering. In this work, we prepared a kind of Ti-Ti3Al metallic composite by in-situ synthesis technology during the SLM (selective laser melting) process, and analyzed its microstructure, wear resistance, microhardness, and compression properties. The results showed that the Ti-Ti3Al composite, prepared by in-situ synthesis technology based on SLM, had more homogeneous Ti3Al-enhanced phase dispersion strengthening structure. The grain size of the workpiece was about 1 μm, and that of the Ti3Al particle was about 200 nm. Granular Ti3Al was precipitated after the aluminum-containing workpiece formed, with a relatively uniform distribution. Regarding the mechanical properties, the hardness (539 HV) and the wear resistance were significantly improved when compared with the Cp-Ti workpiece. The compressive strength of the workpiece increased from 886.32 MPa to 1568 MPa, and the tensile strength of the workpiece increased from 531 MPa to 567 MPa after adding aluminum. In the future, the combination of in-situ synthesis technology and SLM technology can be used to flexibly adjust the properties of Ti-based materials.

Effects of SiO2 Particles in Mechanical Properties of Iron Composite

2013 ◽  
Vol 465-466 ◽  
pp. 886-890
Author(s):  
Adibah Amir ◽  
Othman Mamat
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Fine Particles ◽  
Sintering Temperature ◽  
Silica Particles ◽  
Milling Process ◽  
Powder Metallurgy Technique ◽  
Temperature Changes ◽  
Different Temperatures

Tronohs raw sand was converted into fine silica particles via a series of milling process. Addition of these fine particles into iron composite was found to modify its mechanical properties. The composite was prepared using powder metallurgy technique with varying percentage of silica particles; 5, 10, 15, 20 and 25wt%. The composites were sintered at three different temperatures; 1000° C, 1100° C and 1200° C to find the most suitable sintering temperature. Changes in density and hardness were observed. The results showed that composite consist of 20wt% silica particles and sintered at 1100° C exhibits best improvement.

Preparation and Mechanical Properties of Nano-SiCp/Mg Composites by Ultrasonic Dispersion

2010 ◽  
Vol 150-151 ◽  
pp. 792-795 ◽  
Author(s):  
Hong Yan ◽  
Zhi Hu
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Ultrasonic Method ◽  
Fracture Morphology ◽  
Dispersion Strengthening ◽  
Ultrasonic Dispersion ◽  
Sic Nanoparticles ◽  
The Matrix ◽  
Dislocation Strengthening ◽  
Magnesium Composites

SiC nanoparticles reinforced AZ61 magnesium composites were fabricated by Ultrasonic method. The distribution of nanoparticles in the matrix and the fracture morphology of the composites were observed by SEM, and the mechanical properties of the composites were tested at room temperature. Experimental shows that SiC nanoparticles were dispersed well in the matrix with the pretreatment method. Compared with the matrix, the tensile strength and hardness of the composites were improved respectively. Meanwhile, the ductility of the composites didn’t be obviously decreased. The enhancement function of nano composites was predicted with the dislocation strengthening and Orowan dispersion strengthening mechanisms. The predicted results coincided well with experimental ones.

Characterization and Properties of Iron/Silica-Sand-Nanoparticle Composites

2011 ◽  
Vol 316-317 ◽  
pp. 97-106 ◽  
Author(s):  
Tahir Ahmad ◽  
Othman Mamat
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Powder Metallurgy ◽  
Metal Matrix ◽  
Silica Sand ◽  
Particulate Composites ◽  
Powder Metallurgy Technique ◽  
Superior Mechanical Properties ◽  
Iron Based ◽  
Nanoparticle Composites

Metal matrix-particulate composites fabricated by using powder metallurgy possess a higher dislocation density, a small sub-grain size and limited segregation of particles, which, when combined, result in superior mechanical properties. The present study aims to develop iron based silica sand nanoparticles composites with improved mechanical properties. An iron based silica sand nanoparticles composite with 5, 10, 15 and 20 wt.% of nanoparticles silica sand were developed through powder metallurgy technique. It was observed that by addition of silica sand nanoparticles with 20 wt.% increased the hardness up to 95HRB and tensile strength up to 690MPa. Sintered densities and electrical conductivity of the composites were improved with an optimum value of 15 wt.% silica sand nanoparticles. Proposed mechanism is due to diffusion of silica sand nanoparticles into porous sites of the composites.

Effect of Long-Term Aging on Microstructure and Mechanical Properties of a Wrought Ni-Base Superalloy

2015 ◽  
Vol 816 ◽  
pp. 546-550
Author(s):  
Chao Yuan ◽  
Huan Wang ◽  
Jian Ting Guo ◽  
He Yong Qin
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Room Temperature ◽  
Excellent Thermal Stability ◽  
Good Thermal Stability ◽  
Increasing Trend ◽  
Size And Morphology ◽  
Strength And Plasticity ◽  
Base Superalloy

During long-term and high temperature service, microstructures of superalloys may change and then have an adverse impact on mechanical properties, so the stabilities of a wrought Ni-base superalloy aging without stress at 650°C were investigated in this paper. The results showed that the size and morphology of γ' precipitates in the alloy were not obviously influenced with the increase of exposure time, and primary MC carbides present excellent thermal stability. Moreover, almost no detrimental phase was found. Tensile strength and plasticity at room temperature after aging remained steady. Under the condition of 650°C/823MPa, the stress ruptures life presented increasing trend overall and plasticity decreases slightly. In conclusion, the experiment alloy presents a good thermal stability at 650°C.

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