scholarly journals Effects of Sintering Conditions on Structures and Properties of Sintered Tungsten Heavy Alloy

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2338 ◽  
Author(s):  
Lenka Kunčická ◽  
Radim Kocich ◽  
Zuzana Klečková
Keyword(s):  
Sintering Temperature ◽  
Heavy Alloy ◽  
Tungsten Heavy Alloy ◽  
Fabrication Technology ◽  
Sintering Time ◽  
Heavy Alloys ◽  
Structures And Properties ◽  
Processing Step ◽  
Tungsten Heavy Alloys ◽  
Subsequent Quenching

Probably the most advantageous fabrication technology of tungsten heavy alloys enabling the achievement of required performance combines methods of powder metallurgy and processing by intensive plastic deformation. Since the selected processing conditions applied for each individual processing step affect the final structures and properties of the alloys, their optimization is of the utmost importance. This study deals with thorough investigations of the effects of sintering temperature, sintering time, and subsequent quenching in water on the structures and mechanical properties of a 93W6Ni1Co tungsten heavy alloy. The results showed that sintering at temperatures of or above 1525 °C leads to formation of structures featuring W agglomerates surrounded by the NiCo matrix. The sintering time has non-negligible effects on the microhardness of the sintered samples as it affects the diffusion and structure softening phenomena. Implementation of quenching to the processing technology results in excellent plasticity of the green sintered and quenched pieces of almost 20%, while maintaining the strength of more than 1000 MPa.

scholarly journals Investigation of tungsten heavy alloys using powder metallurgy technique

2021 ◽  
Vol 13 (2) ◽  
pp. 130-136
Author(s):  
Arafa S. Sobha ◽  
◽  
Amr Adela ◽  
Abdelhay Mohameda ◽  
Ali Abd El-Atya ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Process Control ◽  
Sintering Temperature ◽  
Control Agent ◽  
Preparation Condition ◽  
Electrical Contacts ◽  
Nano Particle ◽  
Process Control Agent ◽  
Heavy Alloys ◽  
Tungsten Heavy Alloys

Recently, developing new alloys of Tungsten heavy (WHA) is the most important issue that researchers considered due to their wide applications of radiation protectors, vibration absorber, kinetic energy penetrators and heavy-duty electrical contacts. The present work shows 9 different Tungsten alloys with a variety of weight percent’s from "Graphene" as a Nano- particle additive. The proposed alloys produced by minimizing manufacturing parameters by applying the Taguchi technique. In addition, this work used to relate the Powder-Metallurgy (PM) parameters such as Sintering Temperature (ST) level, the weight % of the added Nano-particle of Graphene (Gw) and the type of Process Control Agent (PCA) with the mechanical characteristics such as Young’s modulus, modulus of Bulk, modulus of Shear, Poisson's number, Vickers hardness, Grain size , Relative Density. The results showed that specimen number 8 is given higher values of modulus of elasticity, reached 326.2 GPa, bulk value of 255.64 GPa, and shear value of 126.7 GPa with PM preparation condition at 15000C sintering temperature, stearic acid as a process control agent (PCA) and 0.0 %Wt. of Graphene.

scholarly journals Microstructure and Properties of Tungsten Heavy Alloy Connections Formed during Sintering with the Participation of the Liquid Phase

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4965
Author(s):  
Paweł Skoczylas ◽  
Zbigniew Gulbinowicz ◽  
Olgierd Goroch
Keyword(s):  
Liquid Phase ◽  
Dissimilar Materials ◽  
Hydrogen Atmosphere ◽  
Parent Material ◽  
Heavy Alloy ◽  
Vacuum Furnace ◽  
Tungsten Heavy Alloy ◽  
Original Material ◽  
Heavy Alloys ◽  
Static Tensile

Tungsten heavy alloys (THA) are used in the defense industry for subcaliber bullet cores due to their high density and strength. Typically methods of joining tungsten rod elements include: soldering, friction welding or threaded sleeve splicing. The properties of the joints were tested for three types of material containing 90.8, 96.2 and 98.2 wt.%. tungsten, density from 17.3 to 18.4 g/cm3 and strength range 400–1000 MPa. Combination in the liquid phase at the sintering temperature was carried out in a vacuum furnace at a temperature of 1520 °C in a hydrogen atmosphere, and tests used pairs of both identical and dissimilar materials. After that, some of the bars were subjected to additional heat treatment at 1100 °C for 3 h. The tests of the mechanical properties in the static tensile test and the measurement of impact strength showed that the obtained strength of the joints was comparable to that of the parent material. The microstructure analysis showed that the resulting joint area, while maintaining the appropriate roughness of the joined end faces of the bars, is homogeneous without areas of the solidified matrix of the joint line. Research showed that it is possible to bond under sintering conditions with the participation of a solid liquid phase of homonymous and dissimilar THA materials. The strength of joints in dissimilar materials was comparable to a tungsten heavy alloy material with lower strength in the bonded pair while homonymous materials were comparable to the original material. The test results provided a good basis for further research in which the obtained pairs of joints will be subjected to plastic working processes.

Preparation and Characterization of Tungsten Heavy Alloy Feedstock for Metal Injection Molding

2007 ◽  
Vol 26-28 ◽  
pp. 363-366 ◽  
Author(s):  
Syed Humail Islam ◽  
Xuan Hui Qu ◽  
M. Tufail
Keyword(s):  
Molecular Weight ◽  
Stearic Acid ◽  
High Density Polyethylene ◽  
Flow Behavior ◽  
Metal Injection Molding ◽  
Tungsten Heavy Alloy ◽  
Shear Rates ◽  
Heavy Alloys ◽  
Tungsten Heavy Alloys

In this study, the effect of various binders’ compositions on the feedstock of pre-alloyed tungsten heavy alloys (WHAs) powders has been investigated. Four kinds of wax-based binders were prepared from paraffin wax (PW), high-density polyethylene (HDPE), polypropylene (PP) and stearic acid (SA), and the characteristic of each feedstock was investigated at various temperatures and shear rates. It was found that all the feedstocks exhibited pseudoplastic flow behavior. Feedstock having multi-polymer components showed better rheological properties than those having mono-polymer because of good wettability between powder and binder, and less sensitivity to temperature and shear rates. This could be due to the molecular weight and length of molecular chain of PP and HDPE.

scholarly journals Effect of Ti on Microstructure and Properties of Tungsten Heavy Alloy Joint Brazed by CuAgTi Filler Metal

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1057
Author(s):  
Yuzhen Lu ◽  
Xiaoming Qiu ◽  
Ye Ruan ◽  
Cui Luo ◽  
Fei Xing
Keyword(s):  
Shear Strength ◽  
Room Temperature ◽  
Filler Metal ◽  
Active Element ◽  
Tungsten Heavy Alloy ◽  
X Ray ◽  
Heavy Alloys ◽  
Tungsten Heavy Alloys ◽  
Poor Area ◽  
Ti Content

In this paper, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractometer (XRD) were used to comprehensively analyze the microstructure and brazing performance of a CuAgTi filler metal with braze tungsten heavy alloys. The association of microstructure, wettability and shear strength of brazing joints was also investigated. With the addition of Ti, the Ti3Cu4 phase appeared in the microstructure of filler metal. Ti is active element that promotes the reaction of filler with tungsten. Therefore, the Ti element is enriched around tungsten and forms a Ti2Cu layer at the interface, leaving a Cu-rich/Ti-poor area on the side. Remaining Ti and Cu elements form the acicular Ti3Cu4 structure at the center of the brazing zone. The wettability of filler metal is improved, and the spreading area is increased from 120.3 mm2 to 320.9 mm2 with the addition of 10 wt.% Ti. The shear strength of joint reaches the highest level at a Ti content of 2.5 wt.%, the highest shear strength is 245.6 MPa at room temperature and 142.2 MPa at 400 °C.

The Effect of Sintering Conditions on the Microstructural Parameters of Particle Composites

2010 ◽  
Vol 129-131 ◽  
pp. 438-444
Author(s):  
S.H. Islam ◽  
M.A. Al-Eshaikh
Keyword(s):  
Sintering Temperature ◽  
Hydrogen Atmosphere ◽  
Intermetallic Phases ◽  
Microstructural Parameters ◽  
Heavy Alloys ◽  
Tungsten Heavy Alloys ◽  
Different Temperatures ◽  
Sintering Conditions ◽  
Co Alloys ◽  
Strength And Ductility

Tungsten heavy alloys are particle composites; they occupy a unique position in materials because of their combination of high density, strength and ductility. The main focus of this study was to examine the effect of sintering conditions (temperature and time) on the microstructural parameters of tungsten heavy alloys. Alloys composed of 88%, 93% and 95% wt. of tungsten and either Ni: Fe (in the ratio of 7:3) or Ni: Co (in the ratio of 7:3) were consolidated into green compacts. Samples of each of the six resulting alloys were sintered in hydrogen atmosphere at different temperatures for different sintering holding times. The microstructural parameters of both types were found to be roughly similar at each temperature and holding time. At higher sintering temperature and longer sintering holding times there was a matrix gradient and the formation of FeNi intermetallic phases at tungsten matrix interfaces. The microstructural parameters showed that the W-Ni-Co alloys may have some advantage as a result of their small tungsten grains and the lower contiguity.

scholarly journals Correlating Microstrain and Activated Slip Systems with Mechanical Properties within Rotary Swaged WNiCo Pseudoalloy

Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 208 ◽  
Author(s):  
Pavel Strunz ◽  
Lenka Kunčická ◽  
Přemysl Beran ◽  
Radim Kocich ◽  
Charles Hervoches
Keyword(s):  
Mechanical Properties ◽  
Thermomechanical Processing ◽  
Radiation Shielding ◽  
Tungsten Heavy Alloy ◽  
Slip Systems ◽  
Soft Matrix ◽  
Heavy Alloys ◽  
Dislocation Densities ◽  
Tungsten Heavy Alloys ◽  
Edge Dislocations

Due to their superb mechanical properties and high specific mass, tungsten heavy alloys are used in demanding applications, such as kinetic penetrators, gyroscope rotors, or radiation shielding. However, their structure, consisting of hard tungsten particles embedded in a soft matrix, makes the deformation processing a challenging task. This study focused on the characterization of deformation behavior during thermomechanical processing of a WNiCo tungsten heavy alloy (THA) via the method of rotary swaging at various temperatures. Emphasis is given to microstrain development and determination of the activated slip systems and dislocation density via neutron diffraction. The analyses showed that the grains of the NiCo2W matrix refined significantly after the deformation treatments. The microstrain was higher in the cold swaged sample (44.2 × 10−4). Both the samples swaged at 20 °C and 900 °C exhibited the activation of edge dislocations with <111> {110} or <110> {111} slip systems, and/or screw dislocations with <110> slip system in the NiCo2W matrix. Dislocation densities were determined and the results were correlated with the final mechanical properties of the swaged bars.

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