Properties of Hot-Pressed Cr-Cr3Si

1994 ◽  
Vol 364 ◽  
Author(s):  
Joseph W. Newkirk ◽  
Joseph E. Price
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Low Temperature ◽  
High Temperatures ◽  
Hot Pressing ◽  
Elevated Temperatures ◽  
Arc Melting ◽  
Cast Alloys ◽  
Strength And Toughness

AbstractPreviously, Cr-Cr3Si in-situ composites produced by arc-melting were shown to have good strengths at high temperatures1. For example, samples of a 25% Cr and 75% Cr3Si composite achieved bend strengths of 135 MPa at 1200°C. However, there is potential for even higher strengths at high temperatures and a need for improvement in the low temperature strength and toughness. In order to improve the properties, two approaches were taken. The first used powder metallurgy to develop a better microstructure than in the cast alloys, to try to improve both strength and toughness. The second approach was to incorporate erbia into the composites, to improve the strength and stability of the microstructure at elevated temperatures.High density samples of hot pressed Cr-15.5Si and Cr-18.6Si have been produced by mixing Cr and Gr3Si powders and hot pressing in a graphite die. Erbia powders have been incorporated into some compacts for comparison.Micros true tures have been characterized and mechanical properties determined. Both the hot pressing and the erbia affected the properties. In addition the erbia had a significant effect on consolidation of the samples.

Effect of TiC Content on the Microstructure and Mechanical Properties of Ti3AlC2/Al2O3 In Situ Composites Synthesized by Hot Pressing

2012 ◽  
Vol 724 ◽  
pp. 278-281 ◽  
Author(s):  
Lan Ye ◽  
Jian Feng Zhu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Composition ◽  
Flexural Strength ◽  
High Temperatures ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Microstructure And Mechanical Properties ◽  
Reactive Hot Pressing

The Ti3AlC2/Al2O3 in situ composites were successfully synthesized from the system of Ti-TiC-Al-TiO2 by reactive hot pressing at 1350 °C. The effect of TiC content on the phase composition, microstructure and mechanical properties were investigated in detail. The results indicate that the fabricated products possess the highest purity as the TiC contents reduce to 90 % of its theoretical content. This deviation is mainly attributed to the decomposition of Ti3AlC2 and vaporization of Al at high temperatures. The effect of TiC content on the fracture toughness, flexural strength, Vickers hardness of Ti3AlC2/Al2O3 composites was also discussed in detail.

scholarly journals Microstructure and mechanical properties of slowly cooled Cu47.5Zr47.5Al5

2007 ◽  
Vol 22 (2) ◽  
pp. 326-333 ◽  
Author(s):  
J. Das ◽  
S. Pauly ◽  
C. Duhamel ◽  
B.C. Wei ◽  
J. Eckert
Keyword(s):  
Mechanical Properties ◽  
Fracture Strain ◽  
Volume Fraction ◽  
Spherical Shape ◽  
High Yield ◽  
High Yield Strength ◽  
Scanning Calorimetry ◽  
Arc Melting ◽  
Martensite Matrix

Cu47.5Zr47.5Al5 was prepared by arc melting and solidified in situ by suction casting into 2–5-mm-diameter rods under various cooling rates (200–2000 K/s). The microstructure was investigated along the length of the rods by electron microscopy, differential scanning calorimetry and mechanical properties were investigated under compression. The microstructure of differently prepared specimens consists of macroscopic spherical shape chemically inhomogeneous regions together with a low volume fraction of randomly distributed CuZr B2 phase embedded in a 2–7 nm size clustered “glassy-martensite” matrix. The as-cast specimens show high yield strength (1721 MPa), pronounced work-hardening behavior up to 2116 MPa and large fracture strain up to 12.1–15.1%. The fracture strain decreases with increasing casting diameter. The presence of chemical inhomogenities and nanoscale “glassy-martensite” features are beneficial for improving the inherent ductility of the metallic glass.

Structure and mechanical properties of cast quasicrystal-reinforced Mg–Zn–Al–Y base alloys

2004 ◽  
Vol 19 (5) ◽  
pp. 1531-1538 ◽  
Author(s):  
Guangyin Yuan ◽  
Kenji Amiya ◽  
Hidemi Kato ◽  
Akihisa Inoue
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Cast Alloy ◽  
Strengthening Mechanism ◽  
Icosahedral Quasicrystal ◽  
Compression Tests ◽  
Strengthening Phase ◽  
Creep Tests ◽  
Cast Alloys ◽  
Bulk Alloys

The structure and mechanical properties of Mg–Zn–Al–Y base cast alloys containing an icosahedral quasicrystal phase (i-phase) as a main strengthening phase were investigated. Mg–8Zn–4Al–xY base bulk alloys containing the i-phase were prepared by casting into a copper mold at moderate cooling rates. The Y addition was effective for decreasing the size of the i-phase and the increasing the homogeneity of its dispersed state. The mechanical properties examined by compression tests at room temperature were much superior to those of a conventional AZ91 Mg alloy. The creep tests at elevated temperatures indicated a promising high temperature creep resistance of the quasicrystal-reinforced Mg–Zn–Al–Y cast alloy. The strengthening mechanism was also discussed.

scholarly journals Effects of High Temperatures on the Physical and Mechanical Properties of Carbonated Ordinary Concrete

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Qifang Xie ◽  
Lipeng Zhang ◽  
Shenghua Yin ◽  
Baozhuang Zhang ◽  
Yaopeng Wu
Keyword(s):  
Mechanical Properties ◽  
Weight Loss ◽  
Elastic Modulus ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Physical And Mechanical Properties ◽  
Surface Characteristics ◽  
Time Service ◽  
Different Temperatures ◽  
Cooling Methods

Fires are always known for seriously deteriorating concrete in structures, especially for those with certain carbonation due to long-time service. In this paper, 75 prism specimens were prepared and divided into four groups (three carbonated groups and one uncarbonated group). Specimens were tested under different temperatures (20, 300, 400, 500, 600, and 700°C), exposure times (3, 4, and 6 hours), and cooling methods (water and natural cooling). Surface characteristics, weight loss rate, and residual mechanical properties (strength, initial elastic modulus, peak, and ultimate compressive strains) of carbonated concrete specimens after elevated temperatures were investigated and compared with that of the uncarbonated ones. Results show that the weight loss rates of the carbonated concrete specimens are slightly lower than that of the uncarbonated ones and that the cracks are increased with raising of temperatures. Surface colors of carbonated concrete are significantly changed, but they are not sensitive to cooling methods. Surface cracks can be evidently observed on carbonated specimens when temperature reaches 400°C. Residual compressive strength and initial elastic modulus of carbonated concrete after natural cooling are generally larger than those cooled by water. The peak and ultimate compressive strains of both carbonated and uncarbonated concrete specimens increase after heating, but the values of the latter are greater than that of the former. Finally, the constitutive equation to predict the compressive behaviors of carbonated concrete after high temperatures was established and validated by tests.

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.

Evaluation of the Influence of Pre-Alloyed Powder Fe65Nb on the Production of Metal Matrices by Powder Metallurgy

2020 ◽  
Vol 1012 ◽  
pp. 3-8
Author(s):  
A.C.G. Silva ◽  
Hellen C.P. Oliveira ◽  
Thales Eduardo Leal ◽  
Paulo Santos Assis
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Chemical Composition ◽  
Solid State ◽  
Hot Pressing ◽  
Physical And Mechanical Properties ◽  
Toxic Element ◽  
Alloyed Powder ◽  
Eds Analysis ◽  
Porosity Measurements

The objective of this paper is to study Fe65Nb-Cu metal matrices, thus varying the content of the pre-alloyed Fe65Nb powder from 10% to 100%. Therefore, powders of Fe65Nb and Cu were used, innovating in the chemical composition of the commonly used matrices. The objective is to evaluate the substitution of Co (toxic element, commonly used) by Nb (98.2% of reserves are Brazilian). For the sintering of the samples it was used hot pressing technique. The parameters were set at: 850°C / 35MPa / 3min. The sintered bodies underwent SEM/EDS analysis and density and porosity measurements were performed. From the results it is possible to say that the compositions of (10% and 30% Fe65Nb) presented the best physical and mechanical properties. The relative density decreases for the compositions with 40%, 50% and 60% Fe65Nb is justified by the presence of fragile particles in metal matrices, since they require more energy in order to efficiently transport matter (diffusion) in a solid state.

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