scholarly journals Nano-Indentation Properties of Tungsten Carbide-Cobalt Composites as a Function of Tungsten Carbide Crystal Orientation

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2137
Author(s):  
Renato Pero ◽  
Giovanni Maizza ◽  
Roberto Montanari ◽  
Takahito Ohmura
Keyword(s):  
Tungsten Carbide ◽  
Crystal Orientation ◽  
Advanced Materials ◽  
Full Density ◽  
Micro Hardness ◽  
Electron Backscattered Diffraction ◽  
Nano Indentation ◽  
Mixture Modelling ◽  
Small Set ◽  
The Relationship

Tungsten carbide-cobalt (WC-Co) composites are a class of advanced materials that have unique properties, such as wear resistance, hardness, strength, fracture-toughness and both high temperature and chemical stability. It is well known that the local indentation properties (i.e., nano- and micro-hardness) of the single crystal WC particles dispersed in such composite materials are highly anisotropic. In this paper, the nanoindentation response of the WC grains of a compact, full-density, sintered WC-10Co composite material has been investigated as a function of the crystal orientation. Our nanoindentation survey has shown that the nanohardness was distributed according to a bimodal function. This function was post-processed using the unique features of the finite mixture modelling theory. The combination of electron backscattered diffraction (EBSD) and statistical analysis has made it possible to identify the orientation of the WC crystal and the distinct association of the inherent nanoindentation properties, even for a small set (67) of nanoindentations. The proposed approach has proved to be faster than the already existing ones and just as reliable, and it has confirmed the previous findings concerning the relationship between crystal orientation and indentation properties, but with a significant reduction of the experimental data.

Study on Microstructure Character in the Deformable Regions of AISI-1045 Steel Fine Blanking with Negative Clearance

2009 ◽  
Vol 628-629 ◽  
pp. 541-546 ◽  
Author(s):  
J.H. Li ◽  
Wei Fu Fan ◽  
Zhong Mei Zhang
Keyword(s):  
Work Piece ◽  
Micro Hardness ◽  
Fine Blanking ◽  
Metallic Crystal ◽  
Aisi 1045 Steel ◽  
Aisi 1045 ◽  
Metal Deformation ◽  
Negative Clearance ◽  
1045 Steel ◽  
The Relationship

This paper obtained work piece of fine blanking with negative clearance by experiment. The microstructure and fractography photograph in regions like rollover zone, shearing band, under sheared surface and fracture band were scanned by instrument of scanning electron microscope (SEM-JSM-6360LV). The fine-blanking with negative clearance makes the metal deformation regions into a state of triaxial stress precise and it causes an intense metallic stream that brings about inter-dislocation and distortion of metallic crystal product under the action of stronger force, so the metallic crystal is reset and the isometric metallic crystal of shearing zone is staved, sloped and pulled and it appears as dense lined and strip crystal. The paper analyzes the full course of producing and development of micro crack in the ejecting stage in the fine-blanking processing of negative clearance. And the course of final rupture is also analyzed. The relationship curve of blanking stroke and micro hardness is measured by Vickers Hardness instrument (MH-6). The deforming principle of fine blanking deformation with negative clearance is analyzed by means of microstructure, metallographic photograph and micro hardness.

scholarly journals EBSD Analysis of Metal Matrix Nanocomposite Microstructure Produced by Powder Metallurgy

Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 878 ◽  
Author(s):  
Íris Carneiro ◽  
Filomena Viana ◽  
Manuel F. Vieira ◽  
José V. Fernandes ◽  
Sónia Simões
Keyword(s):  
Powder Metallurgy ◽  
Advanced Materials ◽  
Sintering Process ◽  
Electron Backscattered Diffraction ◽  
Matrix Microstructure ◽  
Metal Matrix Nanocomposite ◽  
The Matrix ◽  
Dislocation Annihilation ◽  
Metal Nanocomposites ◽  
Matrix Nanocomposite

The development of metal nanocomposites reinforced by carbon nanotubes (CNTs) remains a focus of the scientific community due to the growing need to produce lightweight advanced materials with unique mechanical properties. However, for the successful production of these nanocomposites, there is a need to consolidate knowledge about how reinforcement influences the matrix microstructure and which are the strengthening mechanisms promoting the best properties. In this context, this investigation focuses on the study of the reinforcement effect on the microstructure of an Ni-CNT nanocomposites produced by powder metallurgy. The microstructural evolution was analysed by electron backscattered diffraction (EBSD). The EBSD results revealed that the dispersion/mixing and pressing processes induce plastic deformation in the as-received powders. The dislocation structures produced in those initial steps are partially eliminated in the sintering process due to the activation of recovery and recrystallization mechanisms. However, the presence of CNTs in the matrix has a significant effect on the dislocation annihilation, thus reducing the recovery of the dislocation structures.

scholarly journals Effect of Particle Size on Microstructure and Element Diffusion at the Interface of Tungsten Carbide/High Strength Steel Composites

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4164 ◽  
Author(s):  
Hongmei Zhang ◽  
Hongnan Li ◽  
Ling Yan ◽  
Chao Wang ◽  
Fangfang Ai ◽  
...  
Keyword(s):  
Particle Size ◽  
Tungsten Carbide ◽  
High Strength Steel ◽  
Average Particle Size ◽  
High Strength ◽  
Average Particle ◽  
Micro Hardness ◽  
Vacuum Sintering ◽  
Element Diffusion ◽  
Average Grain Size

The microstructure and micro-hardness of tungsten carbide/high strength steel (WC/HSS) composites with different particle sizes were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), ultra-high temperature laser confocal microscopy (UTLCM) and micro-hardness testing. The composites were prepared by cold pressing and vacuum sintering. The results show that WC density tends to increase as the average grain size of WC decreases and the micro-hardness of WC increases with the decrease of WC particle size. The micro-hardness of WC near the bonding interface is higher than that in other regions. When the particle size of WC powder particles is 200 nm, a transition layer with a certain width is formed at the interface between WC and HSS, and the combination between the two materials is metallurgical. The iron element in the HSS matrix diffuses into the WC structure in contact with it, resulting in a fusion layer of a certain width, and the composite interface is relatively well bonded. When the average particle size of WC powder is 200 nm, W, Fe and Co elements significantly diffuse in the transition zone at the interface. With the increase of WC particle size, the trend of element diffusion decreases.

Surface Modification Process by Electrical Discharge Machining with Tungsten Carbide Powder Mixing in Kerosene Fluid

2019 ◽  
Vol 889 ◽  
pp. 115-122
Author(s):  
Van Tao Le ◽  
Tien Long Banh ◽  
Xuan Thai Tran ◽  
Nguyen Thi Hong Minh
Keyword(s):  
Surface Roughness ◽  
Tungsten Carbide ◽  
Electrical Discharge ◽  
Alloy Powder ◽  
Electrical Discharge Machining ◽  
Carbide Powder ◽  
Micro Hardness ◽  
Hard Materials ◽  
Tungsten Carbide Powder ◽  
Better Than

Electrical discharge machining (EDM) process is widely used to process hard materials in the industry. The process of electrical discharge is changed and called PMEDM when alloy powder is added in the oil dielectric. In the current study, the effect of tungsten carbide alloy powder added in the dielectric on the surface roughness (Ra) and the micro hardness of surface (HV) status of the workpiece SKD61 after machining is investigated. Studies show that the surface roughness and the micro hardness of surface obtained by PMEDM is generally better than that by normal EDM. The method can be applied for improving surface quality such as improving strengthening of molds and machine parts.

Creep Damage Assessment Through EBSD Method and Hardness Measurement for a High Chromium Turbine Rotor Steel Forging

2007 ◽  
Author(s):  
Kazunari Fujiyama ◽  
Takashi Saito ◽  
Keita Mori ◽  
Takahisa Hino ◽  
Ryuichi Ishii
Keyword(s):  
Electron Microscope ◽  
Dislocation Density ◽  
Damage Assessment ◽  
Creep Damage ◽  
Life Assessment ◽  
Rotor Steel ◽  
Creep Tests ◽  
Nano Indentation ◽  
Steel Forging ◽  
The Relationship

10Cr-1Mo-1W-VNbN steel forging for steam turbine rotors was investigated using TEM (Transmission Electron Microscope), SEM (Scanning Electron Microscope) with EBSD (Electron BackScattering Diffraction pattern) method and nano-indentation tester for the assessment of microstructural change during creep damage process. Long term creep rupture tests and interrupted creep tests were conducted for the subject material and then effective damage parameters were assessed and compared with each other. Dislocation substructure which was observed through TEM thin foil method showed increasing lath/block width according to creep damage accumulation and the same feature was observed through EBSD IPF mapping more clearly and easily. EBSD KAM mapping was also conducted and averaged KAM was shown as an effective index for measuring dislocation microstructural changes during creep. Nano-indentation tests were conducted at the same position of EBSD measurement, which revealed that there was a good correlation between hardness value and the square root of averaged KAM. The differential equation of dislocation density with creep time was arranged to estimate the relationship between averaged KAM and time through the relationship between hardness and dislocation density. The creep damage estimation curves were obtained successfully by the equation expressed with stress and temperature term. The dislocation density based creep damage assessment curves could be effective for creep life assessment of high temperature components.

Selecting System Concept by Minimizing Cost of Part Requirement Tolerances

2006 ◽  
Author(s):  
Shun Takai
Keyword(s):  
The Other ◽  
Know How ◽  
System Concept ◽  
Conceptual Design Phase ◽  
Target Values ◽  
Small Set ◽  
The Cost ◽  
The Relationship ◽  
Final System ◽  
Control Part

At the end of a conceptual design phase, engineers choose a single (or a small set of) system concept from a large number of concept variants. In most cases, there is not enough design information to quantitatively evaluate how a final system developed from each concept would perform and cost. Thus engineers need to first perceptually evaluate and select a concept, and then design a system. On the other hand, if engineers know analytical relationships between system and part requirements, they can specify target values of part requirements such that a system achieves its target requirements. Furthermore, if engineers know how much it will cost to control part requirements within tolerances, they can minimize the cost of a system by optimizing tolerances of part requirements. This paper proposes and illustrates an approach to select a system concept when engineers know the relationship between system and part requirements, and how much it will cost to control part requirements within tolerances. Engineers choose a concept that minimizes cost.

scholarly journals Microstructure and Mechanical Properties of Platinum Fiber Fabricated by Unidirectional Solidification

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 216
Author(s):  
Yuui Yokota ◽  
Takayuki Nihei ◽  
Masao Yoshino ◽  
Akihiro Yamaji ◽  
Satoshi Toyoda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Growth Rate ◽  
Crystal Orientation ◽  
Testing Machine ◽  
Tensile Tests ◽  
Maximum Tensile Stress ◽  
Unidirectional Solidification ◽  
Face Centered Cubic ◽  
Electron Backscattered Diffraction ◽  
Microstructure And Mechanical Properties

The microstructure and mechanical properties of platinum (Pt) fibers fabricated by unidirectional solidification using the alloy-micro-pulling-down (A-μ-PD) method were investigated using a Universal Testing Machine and Electron Backscattered Diffraction (EBSD). The Pt fiber fabricated at a growth rate of 10 mm/min was composed of relatively large grains with <100> crystal orientation along the growth direction. The crystal orientation was consistent with the easy axis of the crystal growth on the face-centered-cubic (f.c.c.) structure. On the other hand, the adjacent grains of the Pt fiber fabricated at 50 mm/min were randomly oriented owing to a faster growth rate. In tensile tests, the Pt fibers fabricated by the A-μ-PD method indicated extremely different stress–strain curves compared to the commercial Pt wire. The maximum tensile stress of the Pt fiber reached ~100 MPa, and the Pt fiber ruptured after 58% nominal strain.

scholarly journals Key Role of the Dispersion of Carbon Nanotubes (CNTs) within Epoxy Networks on their Ability to Release

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2530
Author(s):  
Maxime Pras ◽  
Jean-François Gérard ◽  
Luana Golanski ◽  
Guilhem Quintard ◽  
Jannick Duchet-Rumeau
Keyword(s):  
Polymer Matrix ◽  
Interfacial Strength ◽  
Advanced Materials ◽  
Mechanical Reinforcement ◽  
Rheological Analysis ◽  
Polymerization Kinetic ◽  
The Matrix ◽  
Dispersion State ◽  
The Relationship

Carbon nanotube (CNT)-reinforced nanocomposites represent a unique opportunity in terms of designing advanced materials with mechanical reinforcement and improvements in the electrical and thermal conductivities. However, the toxic effects of these composites on human health have been studied, and very soon, some regulations on CNTs and on composites based on CNTs will be enacted. That is why the release of CNTs during the nanocomposite lifecycle must be controlled. As the releasing depends on the interfacial strength that is stronger between CNTs and polymers compared to CNTs in a CNT agglomerate, two dispersion states—one poorly dispersed versus another well dispersed—are generated and finely described. So, the main aim of this study is to check if the CNT dispersion state has an influence on the CNT releasing potential in the nanocomposite. To well tailor and characterize the CNT dispersion state in the polymer matrix, electronic microscopies (SEM and TEM) and also rheological analysis are carried out to identify whether CNTs are isolated, in bundles, or in agglomerates. When the dispersion state is known and controlled, its influence on the polymerization kinetic and on mechanical properties is discussed. It appears clearly that in the case of a good dispersion state, strong interfaces are generated, linking the isolated nanotubes with the polymer, whereas the CNT cohesion in an agglomerate seems much more weak, and it does not provide any improvement to the polymer matrix. Raman spectroscopy is relevant to analyze the interfacial properties and allows the relationship with the releasing ability of nanocomposites; i.e., CNTs poorly dispersed in the matrix are more readily released when compared to well-dispersed nanocomposites. The tribological tests confirm from released particles granulometry and observations that a CNT dispersion state sufficiently achieved in the nanocomposite avoids single CNT releasing under those solicitations.

The relationship between the deformation and the indentation size effect (ISE)

2019 ◽  
Vol 116 (6) ◽  
pp. 622
Author(s):  
Jozef Petrík ◽  
Peter Blaško ◽  
Mária Mihaliková ◽  
Andrea Vasilňáková ◽  
Vojtech Mikloš
Keyword(s):  
Size Effect ◽  
Indentation Size Effect ◽  
Hardness Test ◽  
Longitudinal Axis ◽  
Local Deformation ◽  
Micro Hardness ◽  
Indentation Size ◽  
High Deformation ◽  
The Difference ◽  
The Relationship

The aim of the submitted work is to study the relationship between the local deformation and the indentation size effect (ISE). A local value of reduction of the area (Z) was used as the measure of the deformation. Applied loads in the micro-hardness test ranged between 0.09807 to 0.9807 N. The micro-hardness was measured on the cross section in the longitudinal axis of the fractured sample after the uniaxial tension test. The material of the sample was 99.5% aluminium. The influence of both load and deformation on the ISE was evaluated by the analysis of variance (ANOVA). The influence of the load was also evaluated by Meyer’s index n, PSR method, and Hays–Kendall approach. The influence of both factors on the measured value of micro-hardness and therefore on the ISE is statistically significant. The ISE is normal in the areas with high deformation, on the contrary, in areas with low deformation, it has a “reverse” character. The difference between load independent “true hardness” and measured micro-hardness HV0.05 increases with increasing deformation.

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