scholarly journals Microstructure and Mechanical Properties of High Relative Density γ-TiAl Alloy Using Irregular Pre-Alloyed Powder

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 635
Author(s):  
Mengjie Yan ◽  
Fang Yang ◽  
Boxin Lu ◽  
Cunguang Chen ◽  
Yanli Sui ◽  
...  
Keyword(s):  
Relative Density ◽  
Tial Alloy ◽  
Sintering Temperature ◽  
Low Cost ◽  
Hot Isostatic Pressing ◽  
Duplex Structure ◽  
Sintered Compact ◽  
High Relative Density ◽  
Tih2 Powder ◽  
Al Powder

Preparing high relative density γ-TiAl alloy by pressure-less sintering at low-cost has always been a challenge. Therefore, a new kind of non-spherical pre-alloyed TiAl powder was prepared by the reaction of TiH2 powder and Al powder at 800 °C to fabricate high-density Ti-48Al alloy via pressure-less sintering. The oxygen content was controlled to below 1800 ppm by using coarse Al powder (~120 μm). The sintered densities ranged from 92.1% to 97.5% with sintering temperature varying from 1300 °C to 1450 °C. The microstructure of the sintered compact was greatly influenced by the sintering temperature. The as-sintered samples had a near-γ structure at 1350 °C, a duplex structure at 1400 °C, and a nearly lamellar structure at 1450 °C. To achieve full densification, non-capsule hot isostatic pressing was performed on the 1350 °C and 1400 °C sintered samples. As a result, high compressive strengths of 2241 MPa and 1931MPa were obtained, which were higher than the existing Ti-48Al alloys.

Thermal Expansion of SrZr4-xTix(PO4)6 Ceramics

2018 ◽  
Vol 281 ◽  
pp. 169-174
Author(s):  
Yang Wang ◽  
Yuan Yuan Song ◽  
Yuan Yuan Zhou ◽  
Lu Ping Yang ◽  
Fu Tian Liu
Keyword(s):  
Thermal Expansion ◽  
Relative Density ◽  
Thermophysical Properties ◽  
Sintering Temperature ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
High Relative Density ◽  
Low Thermal Expansion ◽  
Expansion Coefficients

Low thermal expansion ceramics have been widely applied in multiple fields. In this paper, a series of low thermal expansion ceramics SrZr4-xTix(PO4)6 was prepared and characterized. The SrZr4-xTix(PO4)6 ceramics could be well sintered in the temperature range of 1400~1500 °C. The effect of the addition of Ti substituting Zr and the sintering temperature was studied. The Ceramic with x =0.1 sintered at 1450 °C, the SrZr4-xTix(PO4)6 had a high relative density. The thermal expansion coefficients were about 3.301×10-6 °C-1. It was demonstrated that the microstructure of the SrZr4-xTix(PO4)6 could be altered by adding varying amount of Ti to tailor the thermophysical properties of the material.

Compaction of Ti-6Al-4V Powder by ECAE with Back-Pressure

2007 ◽  
Vol 29-30 ◽  
pp. 33-36 ◽  
Author(s):  
Rimma Lapovok ◽  
Dacian Tomus ◽  
Barry C. Muddle
Keyword(s):  
Powder Metallurgy ◽  
Hydrostatic Pressure ◽  
Relative Density ◽  
Shear Deformation ◽  
Vickers Hardness ◽  
Room Temperature ◽  
Low Cost ◽  
Hot Isostatic Pressing ◽  
Back Pressure ◽  
Angular Pressing

Powder metallurgy is widely used to produce alloys with low cost of production. The main drawback using powders is the level of residual porosity of final product which often implies the application of a complicated and costly hot isostatic pressing process. However, this issue can be overcome by using equal channel angular pressing (ECAE) with back pressure (BP). The use of severe shear deformation, with imposed hydrostatic pressure, allows a reduction in the range of compaction temperatures compare to those used in conventional practice. The compaction of Ti-6Al-4V powder by the ECAE method has been investigated. The compaction has been performed at temperatures starting from room temperature (RT) and increasing up to 400°C with various back pressures ranging from 0 to 350MPa. A billet processed by ECAE with 43MPa back-pressure at 400°C was found to have improved relative density of 97.5% and increased Vickers hardness of 369HV, compared to values of 96.7% and 325HV respectively obtained at RT. A relative density of 98.2% and 426HV hardness were measured for billets processed with BP = 262MPa at 400°C. A fully compact billet was obtained by applying 350 MPa of BP at 400°C.

A Novel Forming Process for Powder Metallurgy of Superalloys

2014 ◽  
Vol 622-623 ◽  
pp. 833-839 ◽  
Author(s):  
Qian Bai ◽  
Jian Guo Lin ◽  
Gao Feng Tian ◽  
Daniel S. Balint ◽  
Jin Wen Zou
Keyword(s):  
Powder Metallurgy ◽  
Relative Density ◽  
High Performance ◽  
Low Cost ◽  
Hot Isostatic Pressing ◽  
Hot Extrusion ◽  
Forming Process ◽  
Isostatic Pressing ◽  
Wide Range ◽  
Forming Temperature

Powder metallurgy (PM) of nickel-based superalloys has been used for a wide range of products owing to their excellent special properties in processing and applications. Typical processes for high performance PM superalloys include hot isostatic pressing, hot extrusion and hot isothermal forging. Hot isostatic pressing is normally conducted at a high temperature, by using a low pressure for a long time in a closed vessel, resulting in high cost and low product efficiency. In this paper a novel forming process, i.e. direct powder forging for powder metallurgy of superalloys has been proposed. In this process, the encapsulated and vacuumed powder is heated up to the forming temperature and forged directly to the final shape, by using a high forming load for a very short time. Direct powder forging is a low-cost and energy-saving process compared to conventional PM processes, and in addition, press machines of conventional forging can be used for direct powder forming process. In direct powder forging it is important to control the relative density of the deformed part since the existence of voids could reduce the mechanical strength and fatigue life. In this paper, feasibility tests of direct powder forging are presented. Microstructure, relative density and hardness of the formed specimen were studied.

Study on Preparation and Mechanical Properties of W-Cu Alloy with Low W-W Contiguity

2015 ◽  
Vol 782 ◽  
pp. 77-82 ◽  
Author(s):  
Zhi Yu Hu ◽  
Jin Xu Liu ◽  
Shu Kui Li ◽  
Qing He Zou ◽  
Xing Wang
Keyword(s):  
Strain Rate ◽  
Relative Density ◽  
Failure Strain ◽  
Sintering Temperature ◽  
Electroless Copper Plating ◽  
Cu Alloy ◽  
High Relative Density ◽  
Plasma Sintering ◽  
Plating Method ◽  
Spark Plasma

Electroless copper plating method combined with spark plasma sintering (SPS) was used to fabricate W-Cu alloy with low W-W contiguity. Results show that W-Cu alloy with low W-W contiguity and high relative density can be obtained by this method. With sintering temperature increased from 860°C to 1060°C, the relative density of W-Cu alloy shows a rapidly increasing tendency, but the W-W contiguity keeps at a low level. Compression testing results show that the ductility of prepared W-Cu alloy is sensitive to strain rate, and the failure strain of the W-Cu alloy shows obviously increasing tendency with the loading strain rate increased from 10-3 to 103.

Preparation and Characterization of Zirconia-Based Multi-Phase Nanocomposite

2008 ◽  
Vol 368-372 ◽  
pp. 762-764 ◽  
Author(s):  
Yong Shun Yang ◽  
Yi Ran Liu ◽  
Guo Qing Chen
Keyword(s):  
Relative Density ◽  
Sintering Temperature ◽  
Salt Solutions ◽  
Chemical Homogeneity ◽  
High Relative Density ◽  
Aqueous Salt Solutions ◽  
Multi Phase ◽  
Nanocomposite Powders ◽  
Compressive Tests

ZrO2 (3Y)-CaO-SiO2-TiO2 powders with excellent chemical homogeneity were synthesized by heating the alcohol-aqueous salt solutions. The powders have good dispersion, with particle size of 11~15nm and no hard agglomeration. The nanocomposite powders were hot-pressed in vacuum. The obtained zirconia-based multi-phase nanocomposites were characterized by using XRD and SEM, as well as relative density testing. The results demonstrated that, even though the sintering temperature was as low as 1250°C, a high relative density of 97.5% was achieved. The superplastic compressive tests of the as-sintered specimens demonstrate that this material behaves good deformability at 1350~1500°C, at which the maximum extrusion pressure is lower than 35MPa.

Investigation on the Preparation and Properties of MoCu Gradient Material

2013 ◽  
Vol 749 ◽  
pp. 322-327
Author(s):  
Xiao Hong Yang ◽  
Ni Na Zhang ◽  
Peng Xiao ◽  
Cai Yin You
Keyword(s):  
Electrical Conductivity ◽  
Relative Density ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Gradient Material ◽  
Chemical Compositions ◽  
Sintered Compact ◽  
Gradient Materials ◽  
Combination Methods

In this study, MoCu gradient materials were prepared by the combination methods of liquid phase sintering and permeability copper. The effect of pressure and sintering temperature on the properties of MoCu gradient materials was studied. The physical and mechanical properties of MoCu20/MoCu40 and MoCu20/MoCu30/MoCu40 gradient materials were tested respectively. The results showed that the relative density of green compact and sintered gradient materials increased with the increase of pressing force from 10 tons to 30 tons. The electrical conductivity and hardness of sintered compact achieved the maximum value by the 20 tons. Within the sintering temperature range of 1100 to 1400, the relative density, electrical conductivity and hardness of sintered gradient materials increased with the increase of sintering temperature. The overall properties of sintered materials were obtained at 1350. For two-layer and three-layer MoCu gradient materials, their microstructures and chemical compositions showed a continuously and gradient change. The bending strength and the thermal conductivity of three-layer MoCu gradient materials were better than that of two-layer gradient materials.

Effect of Sintering Temperature on Microstructure and Mechanical Properties of Al2O3-TiC-ZrO2 Ceramic Composites

2012 ◽  
Vol 476-478 ◽  
pp. 1031-1035
Author(s):  
Wei Min Liu ◽  
Xing Ai ◽  
Jun Zhao ◽  
Yong Hui Zhou
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Relative Density ◽  
Sintering Temperature ◽  
Ceramic Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

Al2O3-TiC-ZrO2ceramic composites (ATZ) were fabricated by hot-pressed sintering. The phases and microstructure of the composites were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The relative density and mechanical properties (flexural strength, fracture toughness and Vicker’s hardness) of the composites were tested. The results show that the microstructure of the composites was the gray core-white rim. With the increase of sintering temperature, the relative density and mechanical properties of the composites increased first and then decreased. The composite sintered at 1705°C has the highest synthetical properties, and its relative density, flexural strength, fracture toughness and Vickers hardness are 98.3%,970MPa,6.0 MPa•m1/2and 20.5GPa, respectively.

Figures of Merit of Low-Cost CuAl0.9Fe0.1O2 Thermoelectric Material Prepared at Different Solid State Reaction Sintering Temperatures

2015 ◽  
Vol 659 ◽  
pp. 185-189
Author(s):  
Aparporn Sakulkalavek ◽  
Rungnapa Thonglamul ◽  
Rachsak Sakdanuphab
Keyword(s):  
Figure Of Merit ◽  
Sintering Temperature ◽  
Low Cost ◽  
Uniaxial Pressure ◽  
Rhombohedral Structure ◽  
Second Phase ◽  
X Ray Diffraction ◽  
High Purity Grade ◽  
Average Grain Size ◽  
Xrd Patterns

In this study, we investigated a CuAl0.9Fe0.1O2 compound prepared at two different sintering temperatures in order to find out the effect of sintering temperature on the compound's figure of merit of thermoelectric properties. The thermoelectric CuAl0.9Fe0.1O2 compound was prepared from high purity grade Cu2O, Al2O3 and Fe2O3 powders. The mixture of these powders were ground and then pressed with uniaxial pressure into pellets. The pellets obtained were sintered in the air at 1423 K and 1473 K. X-ray diffraction (XRD) patterns showed a single phase of CuAl0.9Fe0.1O2 with rhombohedral structure, , along with a trace of CuO second phase. Moreover, the XRD peaks of the sample sintered at 1423 K indicated that more Fe3+ atoms replaced Al3+ atoms in this sample than they did in the sample sintered at 1473 K. The average grain size of the CuAl0.9Fe0.1O2 compound prepared increased with increasing sintering temperature, whereas its mean pore size and porosity decreased with increasing sintering temperature. The dispersed small pores markedly decreased the thermal conductivity of the compound, while the Fe3+ substitution of Al3+ increased its electrical conductivity. The highest figure of merit (ZT) found was 0.021 at 973 K in the CuAl0.9Fe0.1O2 sample sintered at 1423 K. Our findings show that this low-cost material with a reasonable figure of merit is a good candidate for thermoelectric applications at high-temperature.

scholarly journals Enhanced Performance of Fly Ash-Based Supports for Low-Cost Ceramic Membranes with the Addition of Bauxite

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 711
Author(s):  
Wan Fan ◽  
Dong Zou ◽  
Jingrui Xu ◽  
Xianfu Chen ◽  
Minghui Qiu ◽  
...  
Keyword(s):  
Fly Ash ◽  
High Performance ◽  
Bending Strength ◽  
Ceramic Membrane ◽  
Sintering Temperature ◽  
Low Cost ◽  
Pure Water ◽  
Ceramic Membranes ◽  
Mullite Phase ◽  
Optimum Balance

Support is a necessary foundation for ceramic membranes to achieve high performance. Finding the optimum balance between high performance and low cost is still a significant challenge in the fabrication of ceramic supports. In this study, low-cost fly ash-based ceramic supports with enhanced performance were prepared by the addition of bauxite. The pore structure, mechanical strength, and shrinkage of fly ash/bauxite supports could be tuned by optimizing the bauxite content and sintering temperature. When the sintering temperature and bauxite content were controlled at 1300 °C and 40 wt%, respectively, the obtained membrane supports exhibited a high pure water permeance of approximately 5.36 m3·m−2·h−1·bar−1 and a high bending strength of approximately 69.6 MPa. At the same time, the optimized ceramic supports presented a typical mullite phase and excellent resistance to acid and alkali. This work provides a potential route for the preparation of ceramic membrane supports with characteristics of low cost and high performance.

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