共查询到20条相似文献,搜索用时 15 毫秒
1.
P. O. Acevedo-Hurtado P. A. Sundaram 《Journal of Materials Engineering and Performance》2017,26(1):69-75
The corrosion behavior of novel Al-Al2O3 MMCs was evaluated in aerated 3.5% NaCl solution through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). These materials corrode almost spontaneously by pitting in aerated 3.5% NaCl solution. Observations indicate that intermetallic particles in these composites appear to play an important role in this pitting corrosion behavior. Addition of Al2O3 particles to the base alloys did not appear to increase their corrosion resistance significantly, although corrosion rate was affected by these reinforcement particles. In cyclic polarization experiments, the small difference between the pitting potentials and the repassivation potentials for these MMCs indicated their low resistance to pitting corrosion. EIS measurements indicate adsorption/diffusion phenomena at the interface of the composites. Electrically equivalent circuits are proposed to describe and substantiate the corrosion processes occurring in these materials. 相似文献
2.
Al2O3–10TiC composite was synthesized by high energy ball milling followed by spark plasma sintering (SPS) process. Microstructure of the sintered composite samples reveals homogeneous distribution of the TiC particles in Al2O3 matrix. Effect of sintering temperature on the microstructure and mechanical properties was studied. The sample sintered at 1500 °C shows a measured density of 99.97% of their theoretical density and hardness of 1892 Hv with very high scratch resistance. These results demonstrate that powder metallurgy combined with spark plasma sintering is a suitable method for the production of Al2O3–10TiC composites. 相似文献
3.
A. A. Mazen 《Journal of Materials Engineering and Performance》1999,8(4):487-495
Aluminum-alumina (Al-Al2O3) metal matrix composite (MMC) materials were fabricated using the powder metallurgy (PM) techniques of hot pressing followed
by hot extrusion. Different reinforcement weight fractions were used, that is, 0, 2.5, 5, and 10 wt% Al2O3. The effect of deformation temperature was investigated through hot tensile deformation conducted at different temperatures.
The microstructures of the tested specimens were also investigated to characterize the operative softening mechanisms.
The yield and tensile strength of the Al-Al2O3 were found to improve as a function of reinforcement weight fraction. With the exception of Al-10wt%Al2O3, the MMC showed better strength and behavior at high temperatures than the unreinforced matrix. The uniform deformation range
was found to decrease for the same reinforcement weight fraction, as a function of temperature. For the same deformation temperature,
it increases as a function of reinforcement weight fraction.
Both dynamic recovery and dynamic recrystallization were found to be operative in Al-Al2O3 MMC as a function of deformation temperature. Dynamic recovery is dominant in the lower temperature range, while dynamic
recrystallization is more dominant at the higher range. The increase in reinforcement weight fraction was found to lead to
early nucleation of recrystallization. No direct relationship was established as far as the number of grains nucleated due
to each reinforcement particle. 相似文献
4.
Dina V. Dudina Vyacheslav I. Mali Alexander G. Anisimov Natalia V. Bulina Michail A. Korchagin Oleg I. Lomovsky Ivan A. Bataev Vladimir A. Bataev 《Metals and Materials International》2013,19(6):1235-1241
We present several possible microstructure development scenarios in Ti3SiC2-Cu composites during mechanical milling and Spark Plasma Sintering (SPS). We have studied the effect of in situ consolidation during milling of Ti3SiC2 and Cu powders and melting of the Cu matrix during the SPS on the hardness and electrical conductivity of the sintered materials. Under low-energy milling, (3–5) vol.%Ti3SiC2-Cu composite particles of platelet morphology formed, which could be easily SPS-ed to 92–95% relative density. Under high-energy milling, millimeter-scale (3–5) vol.%Ti3SiC2-Cu granules formed as a result of in situ consolidation and presented a challenge to be sintered into a bulk fully dense sample; the corresponding SPS-ed compacts demonstrated a finer-grained Cu matrix and more significant levels of hardening compared to composites of the same composition processed by low-energy milling. The 3 vol.% Ti3SiC2-Cu in situ consolidated and Spark Plasma Sintered granules showed an extremely high hardness of 227 HV. High electrical conductivity of the Ti3SiC2-Cu composites sintered from the granules was an indication of efficient sintering of the granules to each other. Partial melting of the Cu matrix, if induced during the SPS, compromised the phase stability and uniformity of the microstructure of the Ti3SiC2-Cu composites and thus it is not to be suggested as a pathway to enhanced densification in this system. 相似文献
5.
Kee Do Woo Jae Hwang Kim Eui Pyo Kwon Min Seok Moon Hyun Bom Lee Tatsuo Sato Zhiguang Liu 《Metals and Materials International》2010,16(2):213-218
To fabricate an Al-V matrix composite reinforced with submicron-sized Al2O3 and AlxVy (Al3V, Al10V) phases, high energy mechanical milling (HEMM) and sintering were employed. By increasing the milling time, the size of
mechanically milled powder was significantly reduced. In this study, the average powder size of 59 μm for Al, and 178 μm for
V2O5 decreased with the formation of a new product, Al-Al2O3-AlxVy, with a size range from 1.3 μm to 2.6 μm formed by the in-situ combustion reaction during sintering of HEM milled Al and
V2O5 composite powders. The in-situ reaction between Al and V2O5 during the HEMM and sintering transformed the Al2O3 and AlxVy (Al3V, Al10V) phases. Most of the reduced V reacted with excess the Al to form AlxVy (Al3V, Al10V) with very little V dissolved into Al matrix. By increasing the milling time and weight percentage of V2O5, the hardness of the Al-Al2O3-AlxVy composite sintered at 1173 K increased. The composite fabricated with the HEMM Al-20wt.%V2O5 composite powder and sintering at 1173 K for 2 h had the highest hardness. 相似文献
6.
Qiang Wang Kevin Spencer Nick Birbilis Ming-Xing Zhang 《Surface & coatings technology》2010,205(1):50-4671
Al-Al2O3 composite coatings were produced on AZ91D magnesium alloy substrates using kinetic metallization (KM), which is a special type of cold spray using a convergent barrel nozzle to attain sonic velocity. The effect of the volume fraction of Al2O3 particles and KM spray temperatures on the microstructure, hardness of the composite coatings, the deposition efficiency, and the bond strength between the coating and substrate was studied. Results show that addition of Al2O3 particles not only significantly improves the density of the coating, but also enhances the deposition efficiency to an optimum value. The bond strength of the composite coatings with the substrate was found to be much stronger than the coating itself, measured using a specially designed lug shear method. Furthermore, based on bond strength data and SEM analysis, higher Al2O3 content resulted in a failure mode transition from adhesive failure to cohesive failure. This is considered a result of a competition between the strengthening of the ceramic reinforcing particles at the coating/substrate interface, and the weakening of coating cohesive strength due to an increase in the proportion of weaker Al-Al2O3 bonds compared with stronger Al-Al bonds. Characterisation of the composite coating in terms of hardness, porosity and microstructure was also conducted. 相似文献
7.
Cold-gas dynamic spraying (“cold spraying”) was used to deposit aluminum-alumina (Al-Al2O3) metal-matrix composite (MMC) coatings onto 6061 Al alloy. The powders consisted of ?45 μm commercially pure Al that was admixed with either 10 μm or agglomerated 20 nm Al2O3 in weight fractions of 25, 50, 75, 90, and 95 wt.%. Scanning electron microscopy (SEM), Vickers microhardness testing, and image analysis were conducted to determine the microstructure, properties, and the volume fractions of reinforcing particles in the coatings, which was then converted to weight fractions. As the weight fraction of the Al2O3 in the coatings increased, the hardness values of the MMC coatings increased. A maximum hardness of 96 ± 10 HV0.2 was observed for the MMC coating that contained the agglomerated 20 nm Al2O3 particles, while a maximum hardness of 85 ± 24 HV0.2 was observed for the coatings with the 10 μm Al2O3 particles. The slight increase in hardness of the coating containing the agglomerated 20 nm Al2O3 particles occurred in a coating of Al2O3 content that was lower than that in the coating that contained the 10 μm reinforcing Al2O3 particles. The increased hardness of the MMC coatings that contained the agglomerated 20 nm Al2O3 particles and at lower reinforcing particle content was attributed to the increased spreading of the nanoagglomerated particles in the coating, which increased load-sharing and reinforcement capability of the particles. These results suggest that the use of nanoagglomerated, reinforcing hard-phase particles in cold-sprayed MMC coatings may be a more efficient alternative to the use of conventional micronsized reinforcing particles. 相似文献
8.
In-Jin Shon Song-Lee Du Jung-Mann Doh Jin-Kook Yoon 《Metals and Materials International》2013,19(5):1041-1045
Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties. As nanomaterials possess high strength, high hardness, excellent ductility and toughness, undoubtedly, more attention has been paid for the application of nanomaterials. Nanopowders of MgO, Al2O3 and SiO2 were made by high energy ball milling. The simultaneous synthesis and consolidation of nanostuctured MgAl2O4-MgSiO3 composites from milled 2MgO, Al2O3 and SiO2 powders was investigated by the pulsed current activated sintering process. The advantage of this process is that it allows very quick densification to near theoretical density and inhibition of grain growth. Highly dense nanostructured MgAl2O4-MgSiO3 composites were produced with a simultaneous application of 80 MPa pressure and a pulsed current of 2000A within 1min. The fracture toughness of MgAl2O4-Mg2SiO4 composites sintered from 60 mol%MgO-20 mol%Al2O3-20mol%SiO2 powders milled for 4 h was 3.2MPa·m1/2. The fracture toughness of MgAl2O4-MgSiO3 composite is higher than that of monolithic MgAl2O4. 相似文献
9.
Al–Cu–Mg/B4 Cp metal matrix composites with reinforcement of up to 20 wt% were produced using the powder metallurgy technique. The effects of reinforcement ratio, reinforcement size, milling time, and compact pressure on the density and porosity of the composites reinforced with 0, 5, 10, and 20 wt% B4 C particles were studied. Moreover, an artificial neural network model has been developed for the prediction of the effects of the manufacturing parameters on the density and porosity of powder metallurgy Al–Cu–Mg/B4 Cp composites. This model can be used for predicting the densification behavior of Al–Cu–Mg/B4 Cp composites produced under reinforcement of different sizes and amounts with various milling times and compact pressures. The mean absolute percentage error for the predicted values did not exceed1.6%. 相似文献
10.
In this study, Al2024-B4C composites containing 0, 5, 10 and 20 wt% of B4C particles with two different particle sizes (d50=49 μm and d50=5 μm) as reinforcement material were produced by a mechanical alloying method. Two new particle distribution models based on the size of reinforcement materials was developed. The microstructure of the Al2024-B4C composites was investigated using a scanning electron microscope. The effects of reinforcement particle size and weight percentage (wt%) on the physical and mechanical properties of the Al2024-B4C composites were determined by measuring the density, hardness and tensile strength values. The results showed that more homogenous dispersion of B4C powders was obtained in the Al2024 matrix using the mechanical alloying technique according to the conventional powder metallurgy method. Measurement of the density and hardness properties of the composites showed that density values decreased and hardness values increased with an increase in the weight fraction of reinforcement. Moreover, it was found that the effect of reinforcement size and reinforcement content (wt%) on the homogeneous distribution of B4C particles is as important as the effect of milling time. 相似文献
11.
A. Daoud M. T. Abou El-Khair A. N. Abdel-Azim 《Journal of Materials Engineering and Performance》2004,13(2):135-143
Aluminum (Al) alloy 7075 reinforced with Al2O3 particles was prepared using the stir casting method. The microstructure of the cast composites showed some degree of porosity
and sites of Al2O3 particle clustering, especially at high-volume fractions of Al2O3 particles. Different squeeze pressures (25 and 50 MPa) were applied to the cast composite during solidification to reduce
porosity and particle clusters. Microstructure examinations of the squeeze cast composites showed remarkable grain refining
compared with that of the matrix alloy. As the volume fraction of particles and applied squeeze pressure increased, the hardness
linearly increased. This increase was related to the modified structure and the decrease in the porosity. The effect of particle
volume fraction and squeeze pressure on the dry-sliding wear of the composites was studied. Experiments were performed at
10, 30, and 50 N with a sliding speed of 1 m/s using a pin-on-ring apparatus. Increasing the particle volume fraction and
squeeze pressure improved the wear resistance of the composite compared with that of the monolithic alloy, because the Al2O3 particles acted as load-bearing constituents. Also, these results can be attributed to the fact that the application of squeeze
pressure during solidification led to a reduction in the porosity, and an increase in the solidification rate, leading to
a finer structure. Moreover, the application of squeeze pressure improved the interface strength between the matrix and Al2O3 particles by elimination of the porosity at the interface, thereby providing better mechanical locking. 相似文献
12.
Selim Co?kun M. Lütfi Öveço?luAuthor vitae 《International Journal of Refractory Metals and Hard Materials》2011,29(6):651-655
In this study, the effect of Y2O3 additions on the microstructural and the physical properties of W-SiC composites was investigated. Powder blends of W—4 wt.% SiC, W—4 wt.% SiC—1 wt.% Y2O3 and W—4 wt.% SiC—5 wt.% Y2O3 were mechanically alloyed (MA'd) using a Spex mill for 24 h. MA'd composite powders were sintered under inert Ar and reducing H2 gas conditions at 1680 °C for 1 h. Microstructural and morphological characterizations of composite powders and sintered samples were carried out via SEM and XRD analyses. Furthermore, density measurements and hardness measurements of sintered samples were carried out. A highest Vickers microhardness value of 11.4 GPa was measured for the sintered W—4 wt.% SiC—5 wt.% Y2O3 while W—4 wt.% SiC sample possessed the highest relative density value of 97.7%. 相似文献
13.
M. Penchal Reddy F. Ubaid R. A. Shakoor A. M. A. Mohamed 《JOM Journal of the Minerals, Metals and Materials Society》2018,70(6):817-822
In the present work, Al metal matrix composites reinforced with Cu-based (Cu50Ti50) amorphous alloy particles synthesized by ball milling followed by a microwave sintering process were studied. The amorphous powders of Cu50Ti50 produced by ball milling were used to reinforce the aluminum matrix. They were examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness and compression testing. The analysis of XRD patterns of the samples containing 5 vol.%, 10 vol.% and 15 vol.% Cu50Ti50 indicates the presence of Al and Cu50Ti50 peaks. SEM images of the sintered composites show the uniform distribution of reinforced particles within the matrix. Mechanical properties of the composites were found to increase with an increasing volume fraction of Cu50Ti50 reinforcement particles. The hardness and compressive strength were enhanced to 89 Hv and 449 MPa, respectively, for the Al-15 vol.% Cu50Ti50 composites. 相似文献
14.
The effects of milling time on the particle size distribution (PSD), densification, microstructure, hardness and fracture toughness of spark plasma sintered (SPS) TiN+graphite ceramic were studied. TiN with varying amount of graphite (1, 3, and 5 wt%) were milled at different milling time (8, 24 and 40 h), thereafter sintered at sintering temperature of 1800 °C, holding time of 10 min and pressure of 50 MPa. The relative density and hardness increased as milling time progressed from 24 to 40 h, however, the relative density, hardness, and particle size decreased after 8 h of milling. The microstructural analyses showed that a fully sintered TiN+graphite compact could be achieved at sintering temperature of 1800 °C, with no significant grain growth. Residual stress effect of TiN+5 wt% graphite composite was analyzed using XRD method and the result indicated that there is no significant residual stress on the sample. The relative density, Vickers hardness and fracture toughness of TiN+ 1 wt% Gr, milled for 40 h were 99.24%, 13.90 GPa and 4.0 MPa.m1/2 respectively. 相似文献
15.
The effects of MoS2 content on microstructure, density, hardness and wear resistance of pure copper were studied. Copper-based composites containing 0–10% (mass fraction) MoS2 particles were fabricated by mechanical milling and hot pressing from pure copper and MoS2 powders. Wear resistance was evaluated in dry sliding condition using a pin on disk configuration at a constant sliding speed of 0.2 m/s. Hardness measurements showed a critical MoS2 content of 2.5% at which a hardness peak was attained. Regardless of the applied normal load, the lowest coefficient of friction and wear loss were attained for Cu/2.5MoS2 composite. While coefficient of friction decreased when the applied normal load was raised from 1 to 4 N at any reinforcement content, the wear volume increased with increasing normal load. SEM micrographs from the worn surfaces and debris revealed that the wear mechanism was changed from mainly adhesion in pure copper to a combination of abrasion and delamination in Cu/MoS2 composites. 相似文献
16.
S. B. Venkata Siva K. L. Sahoo R. I. Ganguly R. R. Dash 《Journal of Materials Engineering and Performance》2012,21(7):1226-1231
Al-Al2O3 (18%) composite was prepared by stir-cast melt technique. The microstructures showed uniform distribution of particulates, dispersed in the matrix. There exists discontinuity (~0.25???m) in the interface between particulates and matrix. The composite was hot forged. Hot working resulted in fine recrystallized microstructure with particulates dispersed along grain boundaries. Formation of pancake microstructure with some inhomogeneity in the microstructure along three faces of the forged composite was observed. The discontinuity across the interface between Al-Al2O3 was reduced to 0.125???m after forging. The as-cast and forged Al-Al2O3 composites showed higher wear resistance than pure Al. In lubricant media, there was no significant wear observed for either the as-cast or forged composite, whereas Al had shown higher wear at 50?N load. 相似文献
17.
S.A. Sajjadi M. Torabi PariziH.R. Ezatpour A. Sedghi 《Journal of Alloys and Compounds》2012,511(1):226-231
Aluminum/alumina composites are used in automotive and aerospace industries due to their low density and good mechanical strength. In this study, compocasting was used to fabricate aluminum-matrix composite reinforced with micro and nano-alumina particles. Different weight fractions of micro (3, 5 and 7.5 wt.%) and nano (1, 2, 3 and 4 wt.%) alumina particles were injected by argon gas into the semi-solid state A356 aluminum alloy and stirred by a mechanical stirrer with different speeds of 200, 300 and 450 rpm. The microstructure of the composite samples was investigated by Optical and Scanning Electron Microscopy. Also, density and hardness variation of micro and nano composites were measured. The microstructure study results revealed that application of compocasting process led to a transformation of a dendritic to a nondendritic structure of the matrix alloy. The SEM micrographs revealed that Al2O3 nano particles were surrounded by silicon eutectic and inclined to move toward inter-dendritic regions. They were dispersed uniformly in the matrix when 1, 2 and 3 wt.% nano Al2O3 or 3 and 5 wt.% micro Al2O3 was added, while, further increase in Al2O3 (4 wt.% nano Al2O3 and 7.5 wt.% micro Al2O3) led to agglomeration. The density measurements showed that the amount of porosity in the composites increased with increasing weight fraction and speed of stirring and decreasing particle size. The hardness results indicated that the hardness of the composites increased with decreasing size and increasing weight fraction of particles. 相似文献
18.
The investigation involves the fabrication of various nano oxide (Y2O3, Al2O3, La2O3) dispersed WNi alloys by mechanical alloying for 10 h and sintering in Ar atmosphere at 1400 °C, 1500 °C for 2 h. The selected composition for the study is W89Ni10(Y2O3)1 (alloy A), W89Ni10(Al2O3)1 (alloy B) and W89Ni10(La2O3)1 (alloy C) (in weight%). Alloy A exhibit least crystallite size and maximum lattice strain at 10 h of milling. The lattice parameter of W exhibits expansion and contraction behavior during the milling. Microstructure of sintered alloys reveals the presence of both faceted and nearly spherical shaped grains. Bimodal grain size distribution is higher in alloy A at 1500 °C as compared to other alloys and 1400 °C sintering temperature. Texture study and Young's Modulus value reveals that hardness of alloy A is higher against alloy B and alloy C. Maximum % relative sintered density, mean hardness, compressive strength of 89%, 5.53 GPa, 2.25 GPa respectively has been achieved in alloy A at 1500 °C. 相似文献
19.
In-Jin Shon In-Yong Ko Hyun-Su Kang Kyung-Tae Hong Jung-Mann Doh Jin-Kook Yoon 《Metals and Materials International》2012,18(1):115-119
Nanopowders of MgO, Al2O3 and SiO2 were made by high energy ball milling. The rapid sintering of nanostuctured Al2O3-MgSiO3 composites was investigated by the high-frequency induction heating sintering process. The advantage of this process is that
it allows very quick densification to near theoretical density and inhibits grain growth. Highly dense nanostructured Al2O3-MgSiO3 composites were produced with the simultaneous application of 80 MPa pressure and the induced output current of total power
capacity (15 kW) within 2 min. The sintering behavior, grain size and mechanical properties of Al2O3-MgSiO3 composites were investigated. 相似文献
20.
To enhance the toughness of the WC-Al2O3 composite, graphene platelets (GPLs) were incorporated to this ceramic composite by using ball milling and hot pressing sintering. The influences of graphene on microstructure and mechanical properties of the WC-Al2O3 composites were investigated. Results of the experiments showed that the grain size of the composite first diminished and then increased gradually along with the increase of graphene content. Both the Vickers hardness and toughness increased first and then diminished along with the increase of graphene content. The optimized composite exhibited the highest Vickers hardness (18.78 GPa) and the highest fracture toughness (11.09 MPa·m1/2) at the indentation load of 294 N (30 kg) when incorporated with 0.3 wt% GPLs, which are about 18.7% and 40.8% higher than that of WC-Al2O3 without GPLs, respectively. However, the relative density of the WC-Al2O3 composites decreased stably along with the increase of graphene content. Agglomeration of GPLs and porosity were observed in the composites with high content, which weakened the properties. The toughening mechanisms are proposed to be crack deflection, crack bridging, graphene pull out and grain refinement. 相似文献