Effect of Nano-Carbides on the Microstructure and Mechanical Properties of Ti(C,N)-Based Cermets

2011 ◽  
Vol 105-107 ◽  
pp. 2071-2075
Author(s):  
Yan Lei ◽  
Jing Fu Liu ◽  
Bing Yang
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Formation Mechanism ◽  
Ostwald Ripening ◽  
Rupture Strength ◽  
The Other ◽  
Homogeneous Microstructure ◽  
Heterogeneous Microstructure ◽  
Transverse Rupture Strength ◽  
Black Core

In this paper, Ti(C,N)-Based cermets with addition of nano-carbides were fabricated by conventional powder metallurgy techniques. Then the mechanical properties, microstructure and corresponding formation mechanism have been investigated. According to the results, the microstructures of sintered cermets are composed of three kinds of hard grains: one with black core/grey shell, one with white core , and the other with no core. In addition, with more nano-carbides adding, the number of white core grains increases and that of black core grains decreases. It is also found that sintered cermets with nano-carbide additions exhibit higher transverse rupture strength and higher hardness than the others originated from much finer and more homogeneous microstructure. However, cermets with nano-micro carbide additions show the most poor mechanical properties among all sintered cermets, including conventional cermets, due to the obviously heterogeneous microstructure. And this can be explained by Ostwald ripening theory.

Application of Different Dispersants in Fabricating Ti(C,N)-Based Cermet Tool Materials

2016 ◽  
Vol 693 ◽  
pp. 535-540 ◽  
Author(s):  
Qing Zhong Xu ◽  
Xing Ai ◽  
Jun Zhao ◽  
Feng Gong ◽  
Xian Hua Tian ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Oleic Acid ◽  
Rupture Strength ◽  
Fracture Morphology ◽  
Homogeneous Microstructure ◽  
Transverse Rupture Strength ◽  
Tool Materials ◽  
Cermet Materials ◽  
Sintered Materials

A good dispersion of powders is crucial to obtain the sintered materials with superior properties. In this paper, the application of different dispersants in fabricating Ti (C,N)-based cermets was investigated. The effect of dispersant on the microstructure and mechanical properties of cermet materials was studied by observing the microstructure, indention cracks and fracture morphology using scanning electron microscope (SEM), and by measuring the transverse rupture strength (TRS), Vickers hardness (HV) and fracture toughness (KIC). The results reveal that the dispersant oleic acid is helpful for the dispersion of Ti (C,N)-based cermet powders, and can contribute to the homogeneous microstructure and stable mechanical properties of the cermet materials. Compared with the cermets fabricated with polyethylene glycol (PEG), the microstructure of cermets fabricated with oleic acid shows more homogeneously distributed Ti (C,N) particles embedded into more evenly spread binder phases without agglomerations of Ti (C,N) grains. The cermets fabricated with oleic acid possess better comprehensive mechanical properties, with higher transverse rupture strength, hardness and a bit lower fracture toughness than the cermets fabricated with PEG.

Microstructure Evolution and Deformation Mechanisms of Harmonic Structure Designed Materials

2016 ◽  
Vol 879 ◽  
pp. 145-150
Author(s):  
Kei Ameyama ◽  
Sanjay Kumar Vajpai ◽  
Mie Ota
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Powder Metallurgy ◽  
Early Stage ◽  
High Strength ◽  
Plastic Instability ◽  
Structure Design ◽  
Harmonic Structure ◽  
Homogeneous Microstructure ◽  
Macro Scale

This paper presents the novel microstructure design, called Harmonic Structure, which gives structural metallic materials outstanding mechanical properties through an innovative powder metallurgy process. Homogeneous and ultra-fine grain (UFG) structure enables the materials high strength. However, such a “Homo-“ and “UFG” microstructure does not, usually, satisfy the need to be both strong and ductile, due to the plastic instability in the early stage of the deformation. As opposed to such a “Homo-and UFG“ microstructure, “Harmonic Structure” has a heterogeneous microstructure consisting of bimodal grain size together with a controlled and specific topological distribution of fine and coarse grains. In other words, the harmonic structure is heterogeneous on micro-but homogeneous on macro-scales. In the present work, the harmonic structure design has been applied to pure metals and alloys via a powder metallurgy route consisting of controlled severe plastic deformation of the corresponding powders by mechanical milling or high pressure gas milling, and subsequent consolidation by SPS. At a macro-scale, the harmonic structure materials exhibited superior combination of strength and ductility as compared to their homogeneous microstructure counterparts. This behavior was essentially related to the ability of the harmonic structure to promote the uniform distribution of strain during plastic deformation, leading to improved mechanical properties by avoiding or delaying localized plastic instability.

Mechanical Properties of WC-Co Cemented Carbide Prepared via Vacuum Sintering

2013 ◽  
Vol 275-277 ◽  
pp. 1917-1920
Author(s):  
Bing Liang Liang ◽  
Yun Long Ai ◽  
Chang Hong Liu ◽  
Nan Jiang
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Relative Density ◽  
Sintering Temperature ◽  
Rupture Strength ◽  
Cemented Carbide ◽  
Vacuum Sintering ◽  
Transverse Rupture Strength ◽  
Temperature Range ◽  
Peak Value

WC-Co cemented carbide specimens were prepared via vacuum sintering. The influences of composition and sintering temperature on phase composition, microstructure and mechanical properties of WC-Co cemented carbide were investigated. The results show that dense specimens were obtained in the sintering temperature range of 1280~1400°C and the relative density reached over 95%. Only WC and Co3W3C (-phase) were detected by XRD without any else phases, even though Co. With the ascended sintering temperature, hardness increased and the transverse rupture strength (TRS) ascended to peak value and then descended. WC-Co cemented carbide with excellent mechanical properties (HRA>90, TRS~700MPa and KIC>10MPa•m1/2) were obtained.

Effect of Oxygen Content in Powders on Microstructure and Mechanical Properties of WC-FeAl Composites Fabricated by Vacuum Sintering Technique

2015 ◽  
Vol 1088 ◽  
pp. 115-119 ◽  
Author(s):  
Ryoichi Furushima ◽  
Kiyotaka Katou ◽  
Koji Shimojima ◽  
Hiroyuki Hosokawa ◽  
Akihiro Matsumoto
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Oxygen Content ◽  
Rupture Strength ◽  
Powder Preparation ◽  
Vacuum Sintering ◽  
Transverse Rupture Strength ◽  
Sintered Composite ◽  
Lower Oxygen ◽  
Effect Of Oxygen

WC-FeAl composites were fabricated by vacuum sintering technique from mixture of WC and FeAl powders containing various oxygen content. Mechanical properties such as hardness, fracture toughness and transverse rupture strength were influenced by the oxygen content in the powders. Control of the oxygen content was succeeded by changing the powder preparation process. Contrary to expectations, the reduction of oxygen content led to degrade the fracture toughness and transverse rupture strength of the composites. This result was attributed to the microstructural change in the sintered composite. The sintered composite of lower oxygen content exhibited WC grain growth or inhomogeneous microstructure, which can be the cause of degradation of those mechanical properties. It was concluded that the oxygen content was one of the key factors to influence the microstructure or mechanical properties of WC-FeAl composites.

Effect of the Ratio of Co to Ni+Co on the Microstructures and Mechanical Properties of Ti(C, N)-Based Cermets

2017 ◽  
Vol 726 ◽  
pp. 292-296 ◽  
Author(s):  
Peng Wu ◽  
Shao Cun Liu ◽  
Xiu Rong Jiang
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Rupture Strength ◽  
Hard Particle ◽  
Core Size ◽  
Transverse Rupture Strength ◽  
X Ray ◽  
The Core ◽  
Scanning Electron

The microstructures of the prepared Ti(C, N)-based cermets with various ratios of Co to Ni+Co were studied using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Mechanical properties such as transverse rupture strength (TRS), fracture toughness (K1C) and hardness (HRA) were also measured. The results showed that when Ni was partly replaced by Co, the core size of hard particle and the thickness of rim phase changed. With the increasing of the ratio of Co to Ni+Co, the porosity of the cermets increased gradually, the fracture toughness of the cermets decreased gradually, the transverse rupture strength increased firstly and then decreased, the hardness changed slightly。When the ratio of Co to Ni+Co was 0.2, the cermets had better transverse rupture strength (TRS), which was characterized by fine grains and the moderate thickness of rim phase in the binder.

Effects of C and Hf Concentration on the Mechanical Properties of Wrought Superalloys Based on NASA IIB-11 Produced From Prealloyed Powders

1976 ◽  
Author(s):  
R. V. Miner
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Gas Turbine ◽  
Rupture Strength ◽  
Gas Turbine Engine ◽  
Turbine Engine ◽  
Grain Sizes

This work describes the effects of C and Hf concentration on the mechanical properties of NASA IIB-11, a candidate material for advanced-temperature gas turbine engine disks. IIB-11 and four alloys of varied C and Hf concentrations were produced as cross-rolled disks from hot-isostatically pressed powder billets. The lower C, higher Hf modification exhibited the best mechanical properties at 760 C and below. These properties were at least equivalent to those of other candidate alloys for advanced temperature disks. Because of their finer grain sizes, all of these powder metallurgy alloys had lower rupture strength, however, than that achieved previously in conventionally processes IIB-11.

scholarly journals Innovative Densification Process of a Fe-Cr-C Powder Metallurgy Steel

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 665
Author(s):  
Federico Simone Gobber ◽  
Jana Bidulská ◽  
Alessandro Fais ◽  
Róbert Bidulský ◽  
Marco Actis Grande
Keyword(s):  
Heat Treatment ◽  
Powder Metallurgy ◽  
Process Parameters ◽  
Rupture Strength ◽  
Mechanical Resistance ◽  
Metallic Materials ◽  
Transverse Rupture Strength ◽  
Sinter Forging ◽  
Metallurgy Steel ◽  
Main Factor

In this study, the efficacy of an innovative ultra-fast sintering technique called electro-sinter-forging (ESF) was evaluated in the densification of Fe-Cr-C steel. Although ESF proved to be effective in densifying several different metallic materials and composites, it has not yet been applied to powder metallurgy Fe-Cr-C steels. Pre-alloyed Astaloy CrM powders have been ad-mixed with either graphite or graphene and then processed by ESF. By properly tuning the process parameters, final densities higher than 99% were obtained. Mechanical properties such as hardness and transverse rupture strength (TRS) were tested on samples produced by employing different process parameters and then submitted to different post-treatments (machining, heat treatment). A final transverse rupture strength up to 1340 ± 147 MPa was achieved after heat treatment, corresponding to a hardness of 852 ± 41 HV. The experimental characterization highlighted that porosity is the main factor affecting the samples’ mechanical resistance, correlating linearly with the transverse rupture strength. Conversely, it is not possible to establish a similar interdependency between hardness and mechanical resistance, since porosity has a higher effect on the final properties.

Effect of Ceramic Powder Size on Microstructure and Mechanical Properties of Ti(C, N)-Based Cermets

2011 ◽  
Vol 335-336 ◽  
pp. 265-272 ◽  
Author(s):  
Bin Zhan ◽  
Ning Liu ◽  
Wei Xu ◽  
Jin Gang Shi
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Rupture Strength ◽  
Ceramic Powder ◽  
Propagation Path ◽  
Powder Size ◽  
Ceramic Powders ◽  
Transverse Rupture Strength ◽  
Fine Powders ◽  
Nano Powder

Four Ti(C, N)-based cermets was fabricated from different size of ceramic powder by the conventional powder metallurgy technique. Microstructure, fracture surfaces and crack propagation path of samples were observed by SEM, and mechanical properties such as transverse rupture strength, hardness and fracture toughness were measured. Results show that with the refinement of the raw TiC/TiN powders, the black cores and ceramic grains tend to be finer, the gains with white core-grey rim structure obviously increase, and the microstructure of cermet becomes inhomogeneous. The cermets fabricated from fine powders possess higher porosities. Compared with the cermets made from micron ceramic powders, the cermets fabricated from ceramic powders containing nano powder possess higher transverse rupture strength and lower fracture toughness. When the cermet is fabricated from micron TiC/nano TiN powders, its combination property is the best.

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