Synthesis of Layered-Ternary Ti2AlC/Al2O3 Composites by an In Situ Reaction and Hot Pressing Sintering

2012 ◽  
Vol 724 ◽  
pp. 315-318 ◽  
Author(s):  
Jian Feng Zhu ◽  
Rui Juan Pan
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Hot Pressing ◽  
Reaction Path ◽  
Molar Ratio ◽  
Pressing Method ◽  
Fine Grain ◽  
The Matrix ◽  
Hot Pressing Sintering

Mo modified Ti2A1C /Al2O3 composites were successfully fabricated from an elemental power mixture of Ti, Al, TiC and MoO3 by an in situ reaction/hot pressing method. The reaction path and effect of the molar ratio of the initial materials on the phase composition were investigated in detail. The as-prepared materials are mainly composed of (Ti1-xMox)2AlC solid solutions, Al2O3, and a small amounts of the Mo rich compounds. It is found that the in situ formed fine Al2O3 particles tend to disperse on the matrix grain boundaries. Compared with the monolithic Ti2A1C, (Ti,Mo)2AlC/10 wt% Al2O3 composite possesses a fine grain sized structure. The Vickers hardness, flexural strength, fracture toughness, and compressive strength of the as composite are 4.75 GPa, 458 MPa, 6.03 MPa·m1/2, 971 MPa, respectively.

Microstructure and Mechanical Properties of TiC/Ti3AlC2 In Situ Composites Prepared by Hot Pressing Method

2015 ◽  
Vol 816 ◽  
pp. 200-204 ◽  
Author(s):  
Miao Miao Ruan ◽  
Xiao Ming Feng ◽  
Tao Tao Ai ◽  
Ning Yu ◽  
Kui Hua
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Sintering Temperature ◽  
Powder Mixtures ◽  
Pressing Method ◽  
Hot Pressing Sintering ◽  
Sintering Method

TiC/Ti3AlC2 composites were successfully prepared by hot-pressing sintering method from the elemental powder mixtures of Ti, Al and TiC. A possible reaction mechanism was investigated by XRD. The density, Vickers hardness, flexural strength, and fracture toughness of the TiC/Ti3AlC2 composites were also measured. At 660 °C, Al melted and reacted with Ti to form TiAl3. At 900 °C, TiAl3 reacted with TiC and Ti to form Ti2AlC. At 1100 °C, Ti2AlC reacted with TiC to form Ti3AlC2. Increasing the sintering temperature, the content of Ti3AlC2 increased. The TiC/Ti3AlC2 composites had excellent performance after sintered at 1100 °C, the density, Vickers hardness, flexural strength and fracture toughness of the composite were 4.35 g/cm3, 4.72 GPa, 566 MPa and 6.18 MPa·m1/2, respectively.

The Effect of Titanium Addition on Microstructure and Properties of Laves Phase Cr2Nb Alloy Synthesized by Hot Pressing

2011 ◽  
Vol 328-330 ◽  
pp. 1102-1108 ◽  
Author(s):  
Xuan Xiao ◽  
Shi Qiang Lu ◽  
Xian Juan Dong ◽  
Ming Gang Huang ◽  
Jun Wei Liu
Keyword(s):  
Fracture Toughness ◽  
Mechanical Alloying ◽  
Hot Pressing ◽  
Laves Phase ◽  
Nominal Composition ◽  
Second Phase ◽  
Titanium Addition ◽  
Fine Grain ◽  
The Matrix ◽  
Homogeneous Composition

The composite materials with a nominal composition of Cr2Nb-24wt.%Ti were fabricated by mechanical alloying followed by hot pressing. The microstructures and properties were investigated on the composites contained with Laves phase prepared through 20 hours mechanical alloying of chromium, niobium and titanium elemental powders and hot pressing at 1250°C for half an hour. The results indicate that the near full-dense Laves phase Cr2(Nb,Ti) based alloy with homogeneous composition and microstructure is obtained by mechanical alloying and hot pressing techniques. The dispersed soft second phase Nb solid solutions with the fine grain size less than 1μm are distributed uniformly on the matrix. The sample has a relative density of 99%, fracture toughness of 5.32MPa•m1/2 and compress strength of 2080MPa. Due to the effect of fine-grain and alloying addition, the toughening of the Cr2(Nb,Ti) based alloy has been fully realized.

Microstructure and Mechanical Properties of Al2O3/TiAl In Situ Composites Doped with Fe2O3

2011 ◽  
Vol 675-677 ◽  
pp. 597-600
Author(s):  
Liu Yi Xiang ◽  
Fen Wang ◽  
Jian Feng Zhu ◽  
Xiao Feng Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Rockwell Hardness ◽  
Powder Mixtures ◽  
Pressing Method ◽  
Fe2o3 Content ◽  
Maximum Value

Al2O3/TiAl in situ composites were successfully prepared by vacuum hot-pressing method with elemental powder mixtures of Ti, Al, TiO2 and Fe2O3. The effect of Fe2O3 addition on the microstructures and mechanical properties of Al2O3/TiAl composites has been investigated. The results show that the Rockwell hardness, flexural strength and fracture toughness of the composites increase with increasing Fe2O3 content. When the Fe2O3 content is 0.84 wt %, the flexural strength and the fracture toughness reach the maximum value of 624 MPa and 6.63 MPa·m1/2, respectively. The improvement of mechanical properties is firstly associated with a more homogeneous and finer microstructure developed by addition of Fe2O3; secondly, it is related to the increase of the ratio of α2-Ti3Al/γ- TiAl matrix phases.

Strength and Toughness of Composite Materials Based on Nickel Aluminide Matrices

1988 ◽  
Vol 133 ◽  
Author(s):  
J. D. Rigney ◽  
P. S. Khadkikar ◽  
J. J. Lewandowski ◽  
K. Vedula
Keyword(s):  
Fracture Toughness ◽  
Composite Materials ◽  
Hot Pressing ◽  
Nickel Aluminide ◽  
Room Temperature ◽  
Matrix Composition ◽  
Matrix Composites ◽  
The Matrix ◽  
Bend Tests

ABSTRACTSeveral nickel aluminide matrix composites were prepared using vacuum hot pressing techniques. The matrix compositions, based on Ni3Al, Ni3Al+B and NiAl, were reinforced with 10 volume % TiB2 particles. Both smooth and notched bend tests were conducted at room temperature on the monolithic as well as the reinforced materials in order to determine the effects of TiB2 reinforcement on both the smooth bend and notched bend properties. TiB2 additions were shown to improve the smooth bend strengths regardless of the matrix composition while notched bend tests, conducted to provide estimates of fracture toughness, revealed somewhat lower values for the composites in comparison to the monolithic materials. Fractographic analyses and in-situ fracture observations of the composites revealed that preferential fracture in regions of clustered TiB2 particles may significantly affect the measured toughnesses.

In Situ Preparation and Mechanical Properties of (ZrB2+ZrC)/Zr3[Al(Si)]4C6 Composites

2014 ◽  
Vol 602-603 ◽  
pp. 438-442
Author(s):  
Lei Yu ◽  
Jian Yang ◽  
Tai Qiu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Coefficient Of Thermal Expansion ◽  
Raw Materials ◽  
Linear Increase ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Uniform Microstructure

Fully dense (ZrB2+ZrC)/Zr3[Al (Si)]4C6 composites with ZrB2 content varying from 0 to 15 vol.% and fixed ZrC content of 10 vol.% were successfully prepared by in situ hot-pressing in Ar atmosphere using ZrH2, Al, Si, C and B4C as raw materials. With the increase of ZrB2 content, both the bending strength and fracture toughness of the composites increase and then decrease. The synergistic action of ZrB2 and ZrC as reinforcements shows significant strengthening and toughing effect to the Zr3[Al (Si)]4C6 matrix. The composite with 10 vol.% ZrB2 shows the optimal mechanical properties: 516 MPa for bending strength and 6.52 MPa·m1/2 for fracture toughness. With the increase of ZrB2 content, the Vickers hardness of the composites shows a near-linear increase from 15.3 GPa to 16.7 GPa. The strengthening and toughening effect can be ascribed to the unique mechanical properties of ZrB2 and ZrC reinforcements, the differences in coefficient of thermal expansion and modulus between them and Zr3[Al (Si)]4C6 matrix, fine grain strengthening and uniform microstructure derived by the in situ synthesis reaction.

Mechanical responses of microencapsulated self-healing cementitious composites under compressive loading based on a micromechanical damage-healing model

2021 ◽  
pp. 105678952110112
Author(s):  
Kaihang Han ◽  
Jiann-Wen Woody Ju ◽  
Yinghui Zhu ◽  
Hao Zhang ◽  
Tien-Shu Chang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Micromechanical Model ◽  
Cementitious Composites ◽  
Self Healing ◽  
Damage Degree ◽  
Healing Efficiency ◽  
The Matrix ◽  
Healing Agent ◽  
Damage Healing

The cementitious composites with microencapsulated healing agents have become a class of hotspots in the field of construction materials, and they have very broad application prospects and research values. The in-depth study on multi-scale mechanical behaviors of microencapsulated self-healing cementitious composites is critical to quantitatively account for the mechanical response during the damage-healing process. This paper proposes a three-dimensional evolutionary micromechanical model to quantitatively explain the self-healing effects of microencapsulated healing agents on the damage induced by microcracks. By virtue of the proposed 3 D micromechanical model, the evolutionary domains of microcrack growth (DMG) and corresponding compliances of the initial, extended and repaired phases are obtained. Moreover, the elaborate studies are conducted to inspect the effects of various system parameters involving the healing efficiency, fracture toughness and preloading-induced damage degrees on the compliances and stress-strain relations. The results indicate that relatively significant healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will lead to a higher compressive strength and stiffness. However, the specimen will break owing to the nucleated microcracks rather than the repaired kinked microcracks. Further, excessive higher values of healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will not affect the compressive strength of the cementitious composites. Therefore, a stronger matrix is required. To achieve the desired healing effects, the specific parameters of both the matrix and microcapsules should be selected prudently.

scholarly journals Fabrication of Ti3AlC2/Al2O3 nanocomposite by a novel method

2011 ◽  
Vol 43 (3) ◽  
pp. 289-294 ◽  
Author(s):  
J. Zhu ◽  
L. Ye ◽  
F. Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Hot Pressing ◽  
Reaction Path ◽  
Raw Materials ◽  
High Energy ◽  
Good Combination ◽  
High Energy Milling ◽  
Al2o3 Composite ◽  
Novel Method

A Ti3AlC2/Al2O3 nanocomposite was synthesized using Ti, Al, C and TiO2 as raw materials by a novel combination of high-energy milling and hot pressing. The reaction path of the 3Ti-8C-16Al-9TiO2 mixture of powders was investigated, and the results show that the transitional phases TiC, TixAly and Al2O3 are formed in high-energy milling first, and then TixAly is transformed to the TiAl phase during the hot pressing. Finally, a reaction between TiC and TiAl occurs to produce Ti3AlC2 and the nanosized Ti3AlC2/Al2O3 composite is synthesized. The Ti3AlC2/Al2O3 composite possessed a good combination of mechanical properties with a hardness of 6.0 GPa, a flexural strength of 600 MPa, and a fracture toughness (K1C) of 5.8 MPa?m1/2. The strengthening and toughening mechanisms were also discussed.

Self-Toughness Porous Sodium Titanate Bioceramics Prepared via In Situ Grown Na2Ti6O13 Rods

2017 ◽  
Vol 727 ◽  
pp. 806-814 ◽  
Author(s):  
Xiao Wei Ma ◽  
Jian Xing Shen ◽  
Ke Chang Zhang ◽  
Ling Kai Kong ◽  
Jia Le Sun ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Sodium Titanate ◽  
The Novel ◽  
Ceramic Samples ◽  
Porous Bioceramic ◽  
Different Temperatures ◽  
Growth Method ◽  
Titanate Ceramics

Here in, we report the porous bioceramic with Na2Ti6O13 rods prepared by in‒situ growth method. The samples were prepared using cold uniaxial pressing (40 MPa) technique and further sintered at different temperatures. The structure and morphology were characterized by XRD and SEM. The porosity, compressive strength and fracture toughness were also investigated. The bone-like apatite deposition ability of the fabricated ceramic samples was evaluated by Kokubo simulated body fluid (SBF) soaking method. The results indicated that the Na2Ti6O13 rods with about 1‒3 μm in diameter are uniformly distributed in the self‒toughness porous sodium titanate ceramics (SPSTC). The SPSTC with a porosity of 61.10±1.12 % exhibits good compressive strength (43.36±2.43 MPa) and fracture toughness (3.47±0.21 MPa·m1/2). The results indicate that the novel SPSTC scaffolds are promising for bone tissue engineering applications.

Effect of BN Short Fiber Content on Mechanical Properties of ZrB2-SiC UHTCs

2012 ◽  
Vol 512-515 ◽  
pp. 706-709 ◽  
Author(s):  
Chang Ling Zhou ◽  
Yan Yan Wang ◽  
Zhi Qiang Cheng ◽  
Chong Hai Wang ◽  
Rui Xiang Liu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Scanning Electron Microscopy ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Ceramic Composites ◽  
Short Fiber ◽  
Hot Pressing Sintering ◽  
Scanning Electron

ZrB2-20%volSiC ceramic composites with different volume of BN short fiber were fabricated by the hot-pressing sintering under 2000°C. The content of BN short fiber changed from 0 to 15vol%. The density, flexural strength, fracture toughness and thermal expansions coefficient were studied. The microstructures of the samples were observed by scanning electron microscopy. The results show that the introducing of BN short fiber into the ZrB2-20%volSiC lead to a serious of change to the mechanical properties of the ceramic. When the content of the BN short fiber is 10vol%, the flexural strength and fracture toughness reach 422.1MPa and 6.15 MPa•m 1/2 respectively. And the mechanism of the increasing toughness was studied.

scholarly journals The effect of various Co contents on the microstructure and properties of Ti(C,N)-TiB2-Co cermets prepared in situ via reactive hot pressing

2020 ◽  
Vol 12 (5) ◽  
pp. 168781402092571
Author(s):  
Xianrui Zhao ◽  
Ze Yu ◽  
Dunwen Zuo ◽  
Qintao Li ◽  
Mengxian Zhang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Relative Density ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Hardness Test ◽  
Reactive Hot Pressing ◽  
Compacting Pressure ◽  
Vickers Hardness Test ◽  
Scanning Electron

Ti(C,N)-TiB2-Co cermets were in situ synthesized, via reactive hot pressing from the Co-Ti-C-BN system, with a Co content ranging from 6 to 22 wt%. The microstructure, relative density, hardness, and fracture toughness of the sintered compacts was investigated by light microscopy, scanning electron microscopy, ceramic densitometry, and Vickers hardness test. The investigations indicate that during hot pressing (compacting pressure = 30 MPa), when the Co content is 14–22 wt%, the metal binder is extruded. Co and Ti are included in the extrudate, breaking the original ratio and deteriorating the properties of the sintered products. As the Co content increases from 6 wt% to 12 wt%, the porosity increases, and the relative density increases from 97.2% to 99.5%. The fracture toughness increases from 6.1 to 6.8 MPa m1/2. The Vickers hardness first increases from 1897 HV10 to the maximum 1960 HV10 and then decreases slightly to 1945 HV10.

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