scholarly journals Rapidly Solidified Aluminium Alloy Composite with Nickel Prepared by Powder Metallurgy: Microstructure and Self-Healing Behaviour

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4193 ◽  
Author(s):  
Alena Michalcová ◽  
Anna Knaislová ◽  
Jiří Kubásek ◽  
Zdeněk Kačenka ◽  
Pavel Novák
Keyword(s):  
Yield Strength ◽  
Intermetallic Phases ◽  
Ultimate Tensile Stress ◽  
Self Healing ◽  
Offset Yield Strength ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Pass Through ◽  
Rapidly Solidified ◽  
Al Matrix

Composite material prepared by spark plasma sintering (SPS) from a powder mixture of AlCrFeSi rapidly solidified alloy and 5 wt. % of Ni particles was studied in this work. It was proven that during SPS compaction at 500 °C, no intermetallic phases formed on the surface of Ni particles. The material exhibited sufficient mechanical properties obtained by tensile testing (ultimate tensile stress of 203 ± 4 MPa, ductility of 0.8% and 0.2% offset yield strength of 156 ± 2 MPa). Tensile samples were pre-stressed to 180 MPa and annealed at 450 and 550 °C for 1 h. Annealing at 450 °C did not lead to any recovery of the material. Annealing at 550 °C caused the full recovery of 0.2% offset yield strength, while the ductility was decreased. The self-healing behaviour originates from the growth of intermetallic phases between the Ni particle and the Al matrix. The sequence of NiAl, Ni2Al3 and NiAl3 intermetallic phases formation was observed. In particular, the morphology of the NiAl3 phase, growing in thin dendrites into the Al matrix, is suitable for the closing of cracks, which pass through the material.

scholarly journals Self-Healing of SiC-Al2O3-B4C Ceramic Composites at Low Temperatures

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 652
Author(s):  
Baoguo Wang ◽  
Rong Tu ◽  
Yinglong Wei ◽  
Haopeng Cai
Keyword(s):  
Flexural Strength ◽  
Low Temperatures ◽  
Ceramic Composite ◽  
Ceramic Composites ◽  
Self Healing ◽  
Vickers Indentation ◽  
Crack Healing ◽  
Practical Applications ◽  
Plasma Sintering ◽  
Spark Plasma

Self-healing ceramics have been researched at high temperatures, but few have been considered at lower temperatures. In this study, SiC-Al2O3-B4C ceramic composite was compacted by spark plasma sintering (SPS). A Vickers indentation was introduced, and the cracks were healed between 600 °C and 800 °C in air. Cracks could be healed completely in air above 700 °C. The ceramic composite had the best healing performance at 700 °C for 30 min, recovering flexural strength of up to 94.2% of the original. Good crack-healing ability would make this composite highly useful as it could heal defects and flaws autonomously in practical applications. The healing mechanism was also proposed to be the result of the oxidation of B4C.

scholarly journals Compressive strength and thermal properties of spark plasma sintered Al-Al2O3 nanocomposite

2018 ◽  
Vol 50 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Nouari Saheb ◽  
Muhammad Khan
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Thermal Properties ◽  
Yield Strength ◽  
Coefficient Of Thermal Expansion ◽  
Testing Machine ◽  
Thermal Constant ◽  
Compressive Properties ◽  
Plasma Sintering ◽  
Spark Plasma

In this work, compressive and thermal properties of aluminum, milled aluminum, and Al-10Al2O3 composite processed via ball milling (BM) and spark plasma sintering (SPS) were investigated. The microstructural features of powders and sintered samples were characterized using optical and scanning electron microscopy. A universal testing machine was used to determine the compressive properties of the consolidated samples. The thermal conductivity and coefficient of thermal expansion of the developed materials were characterized using a hot disc thermal constant analyzer and a dilatometer, respectively. The Al-10Al2O3 composite possessed hardness of 1309.7 MPa, yield strength of 311.4 MPa, and compressive strength of 432.87 MPa compared to hardness of 326.3 MPa, yield strength of 74.33 MPa, and compressive strength of 204.43 MPa for aluminum. The Al-10Al2O3 composite had thermal conductivity value 81.42 W/mK compared to value of 198.09 W/mK for aluminum. In the temperature range from 373 K to 723 K, the composite had lower CTEs ranging from 10 ? 10?6 to 22 ? 10?6/K compared to 20 ? 10?6 to 30 ? 10?6/K for aluminum.

Examination of microstructure evolution and strengthening mechanisms in an aluminum-based hybrid composite prepared through the spark plasma sintering method

2020 ◽  
Vol 117 (6) ◽  
pp. 613
Author(s):  
Mohammad Reza Rezaei ◽  
Alireza Albooyeh ◽  
Hassan Shiraghaei ◽  
Misagh Shayestefar
Keyword(s):  
Yield Strength ◽  
Spark Plasma Sintering ◽  
Hybrid Composite ◽  
Full Density ◽  
Interfacial Region ◽  
Strengthening Mechanisms ◽  
Consolidation Process ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
The Difference

A bulk hybrid composite to be potentially used as a foam precursor was produced in this study. TiH2 powder particles along with different concentrations of SiC were mixed with pure Al particles and consolidated through the spark plasma sintering (SPS) method. Bulk samples with nearly full density were successfully produced using the SPS method. During the consolidation process, no additional phases were found within the ceramic particles/matrix interfacial region. Using the ceramic TiH2 and SiC particles as the reinforcement cause notably strengthened the pure Al matrix (37% higher yield strength) without adversely affecting the plasticity, helping retain strain to fracture of about 50% for the sample. The yield strength of the samples was quantitatively approximated by examining their strengthening mechanisms via a number of simplified models available in the literature. The analyses found grain boundary and dislocation strengthening to be the most effective mechanisms for enhancing the strength of the samples; it was also found that the difference between the approximated and experimentally obtained overall yield strength was negligible.

scholarly journals Passive Film Properties of Bimodal Grain Size AA7075 Aluminium Alloy Prepared by Spark Plasma Sintering

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3236
Author(s):  
Wenming Tian ◽  
Zhonglei Li ◽  
HuiFeng Kang ◽  
Fasong Cheng ◽  
Fangfang Chen ◽  
...  
Keyword(s):  
Passive Film ◽  
Aluminium Alloys ◽  
Defect Density ◽  
Intermetallic Phases ◽  
Coarse Grain ◽  
Fine Grain ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintered Alloys ◽  
Bimodal Grain Size

The bimodal-grain-size 7075 aluminium alloys containing varied ratios of large and small 7075 aluminium powders were prepared by spark plasma sintering (SPS). The large powder was 100 ± 15 μm in diameter and the small one was 10 ± 5 μm in diameter. The 7075 aluminium alloys was completely densified under the 500 °C sintering temperature and 60 MPa pressure. The large powders constituted coarse grain zone, and the small powders constituted fine grain zone in sintered 7075 aluminium alloys. The microstructural and microchemical difference between the large and small powders was remained in coarse and fine grain zones in bulk alloys after SPS sintering, which allowed for us to investigate the effects of microstructure and microchemistry on passive properties of oxide film formed on sintered alloys. The average diameter of intermetallic phases was 201.3 nm in coarse grain zone, while its vale was 79.8 nm in fine grain zone. The alloying element content in intermetallic phases in coarse grain zone was 33% to 48% higher than that on fine grain zone. The alloying element depletion zone surrounding intermetallic phases in coarse grain zone showed a bigger width and a more severe element depletion. The coarse grain zone in alloys showed a bigger electrochemical heterogeneity as compared to fine grain zone. The passive film formed on coarse grain zone had a thicker thickness and a point defect density of 2.4 × 1024 m−3, and the film on fine grain zone had a thinner thickness and a point defect density of 4.0 × 1023 m−3. The film resistance was 3.25 × 105 Ωcm2 on coarse grain zone, while it was 6.46 × 105 Ωcm2 on fine grain zone. The passive potential range of sintered alloys increased from 457 mV to 678 mV, while the corrosion current density decreased from 8.59 × 10−7 A/cm2 to 6.78 × 10−7 A/cm2 as fine grain zone increasing from 0% to 100%, which implied that the corrosion resistance of alloys increased with the increasing content of fine grains. The passive film on coarse grain zone exhibited bigger corrosion cavities after pitting initiation compared to that on fine grain zone. The passive film formed on fine grain zone showed a better corrosion resistance. The protectiveness of passive film was mainly determined by defect density rather than the thickness in this work.

Properties Improvement of Spark Plasma Sintered Ti-7Al-1Mo Ternary Alloy by TiN Nanoparticles Addition

2021 ◽  
Vol 55 ◽  
pp. 150-158
Author(s):  
Samson Olaitan Jeje ◽  
Mxolisi Brendon Shongwe ◽  
Azeez Lawan Rominiyi ◽  
Peter Apata Olubambi
Keyword(s):  
Electron Microscopy ◽  
Yield Strength ◽  
Ternary Alloy ◽  
Lamellar Structure ◽  
Compressive Yield Strength ◽  
Weight Percentage ◽  
Β Phase ◽  
Plasma Sintering ◽  
Tin Nanoparticles ◽  
Spark Plasma

Titanium (Ti) alloys are materials of interest in structural and chemical applications due to their low density, outstanding mechanical and chemical resistance properties. However, the mechanical properties still need to be enhanced to make them suitable as a replacement for Ni-based superalloys. There have been significant breakthroughs in the reinforcement of Ti alloy with a small weight percentage (wt.%) of ceramics. This work investigates the effect of TiN nanoparticles’ addition on the densification, phase transformation, microstructure, hardness, and compressive properties of Ti-7Al-1Mo ternary alloy. 3 wt.% of TiN nanoparticles was blended with Ti-7Al-1Mo powder, and the resulting admixed powder was consolidated via spark plasma sintering technique at 50 MPa pressure, 10 min holding time, and 1000 °C temperature. Scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry were used to characterise the microstructure and phase composition respectively. The microstructure of Ti-7Al-1Mo revealed a lamellar structure with alpha (α) phase and minor beta (β) phase with visible grain boundaries, while TiN reinforced Ti-7Al-1Mo composite microstructure shows a bimodal structure with reduction in the lamellar structure. Ti-7Al-1Mo ternary alloy has a hardness value of 352±17 HV0.1 and a compressive yield strength of 985±31 MPa. The composite shows an increment of 74 HV and 323 MPa in its hardness and compressive yield strength respectively in comparison to the ternary alloy.

Thermal Conductivity of Cubic Boron Nitride (cBN) Particle Dispersed Al Matrix Composites Fabricated by SPS

2016 ◽  
Vol 879 ◽  
pp. 2413-2418 ◽  
Author(s):  
Kiyoshi Mizuuchi ◽  
Kanryu Inoue ◽  
Yasuyuki Agari ◽  
Motohiro Tanaka ◽  
Takashi Takeuchi ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Boron Nitride ◽  
Volume Fraction ◽  
Cubic Boron Nitride ◽  
Matrix Composites ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Al Matrix Composites ◽  
Al Matrix Composite ◽  
Al Matrix

Cubic boron nitride (cBN) particle-dispersed-aluminum (Al) matrix composites were fabricated from the powder mixture composed of cBN, pure Al and Al-5mass% Si alloy in liquid and solid co-existent state by spark plasma sintering (SPS) process. Al/cBN composites were well consolidated by heating at a temperature range between 798 K and 876 K for 1.56 ks by SPS. Microstructures of the composites produced were examined by scanning electron microscopy and the reaction between the cBN particle and the Al matrix was not detected. The relative packing density of the Al/cBN composite was higher than 99 % in a volume fraction range of cBN up to 45 %. The thermal conductivity of the composite increased with increasing the cBN content in the composite in a volume fraction range of cBN between 35 and 45 vol. %. The highest thermal conductivity of 305 W/mK was obtained for Al matrix composite containing 45 vol.% cBN particles.

Mechanical properties of Mg-based materials fabricated by mechanical milling and spark plasma sintering

2018 ◽  
Vol 233 (10) ◽  
pp. 1972-1984 ◽  
Author(s):  
Mutlu Karasoglu ◽  
Serdar Karaoglu ◽  
Gursoy Arslan
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Spark Plasma Sintering ◽  
Mechanical Milling ◽  
Microstructural Analysis ◽  
Compressive Yield Strength ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Hardness Values

In this work, magnesium powders of different grain sizes were synthesized by mechanical milling for periods ranging from 0.5 to 30 h. Subsequent to milling, powders were consolidated by spark plasma sintering at 550 ℃ for 10 min. Before and after sintering, microstructural changes were investigated by analytical methods including X-ray diffraction (XRD), X-ray spectrometer, optical and electron microscopy. Analyses showed that nanocrystalline sizes were achieved by mechanical milling for milling times exceeding 5 h. Additionally, it was recognized that grain growth occurred during sintering, but to a limited extent. Mechanical test results displayed reasonable improvements in both compressive yield strength and hardness values with increasing milling times up to 5 h, where these reached their maximum values (245.5 MPa and 75.9 HV). The enhancement in these properties with increased milling time up to 5 h was attributed to both the extent of grain refinement and the formation of MgO together with incorporation of Fe particles, originating from the milling process, into the matrix. On the other hand, a substantial decrease in yield strength and hardness values in the samples milled in excess of 5 h were recorded, which in turn was related to the accompanying decline in bulk density of the samples. Microstructural analysis of the deformed samples revealed that grain size reduction suppressed twin formation, which elucidates the enhancement in ductility with decreasing grain size.

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