Spark Plasma Sintering of High-Energy Ball-Milled ZrB2 and HfB2 Powders with 20vol% SiC

2018 ◽  
Vol 941 ◽  
pp. 1990-1995
Author(s):  
Naidu V. Seetala ◽  
Cyerra L. Prevo ◽  
Lawrence E. Matson ◽  
Thomas S. Key ◽  
Ilseok I. Park
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
Micro Hardness ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball ◽  
Ball Milling Time

ZrB2 and HfB2 with incorporation of SiC are being considered as structural materials for elevated temperature applications. We used high energy ball milling of micron-size powders to increase lattice distortion enhanced inter-diffusion to get uniform distribution of SiC and reduce grain growth during Spark Plasma Sintering (SPS). High-energy planetary ball milling was performed on ZrB2 or HfB2 with 20vol% SiC powders for 24 and 48 hrs. The particle size distribution and crystal micro-strain were examined using Dynamic Light Scattering Technique and x-ray diffraction (XRD), respectively. XRD spectra were analyzed using Williamson-Hall plots to estimate the crystal micro-strain. The particle size decreased, and the crystal micro-strain increased with the increasing ball milling time. The SPS consolidation was performed at 32 MPa and 2,000°C. The SEM observation showed a tremendous decrease in SiC segregation and a reduction in grain size due to high energy ball milling of the precursor powders. Flexural strength of the SPS consolidated composites were studied using Four-Point Bend Beam test, and the micro-hardness was measured using Vickers micro-indenter with 1,000 gf load. Good correlation is observed in SPS consolidated ZrB2+SiC with increased micro-strain as the ball milling time increased: grain size decreased (from 9.7 to 3.2 μm), flexural strength (from 54 to 426 MPa) and micro-hardness (from 1528 to 1952 VHN) increased. The correlation is less evident in HfB2+SiC composites, especially in micro-hardness which showed a decrease with increasing ball milling time.

Bulk Nanocrystalline Cu Produced by High-Energy Ball Milling

2011 ◽  
Vol 682 ◽  
pp. 25-32
Author(s):  
Cai Ju Li ◽  
Xin Kun Zhu ◽  
Jing Mei Tao ◽  
H.L. Tang ◽  
T.L. Chen
Keyword(s):  
Grain Size ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
Crystal Defects ◽  
High Energy Ball Milling ◽  
Energy Ball ◽  
Bulk Nanocrystalline ◽  
Pure Cu ◽  
Ball Milling Time

The preparation, mechanical properties, grain size and thermal property of bulk nanocrystalline Cu (BNC-Cu) were investigated in this paper. BNC-Cu can be produced by in situ consolidation of pure Cu powder with high-energy ball milling at room temperature; the average grain sizes of Cu samples decreased with the increasing of ball milling time before 9 h because the grain refining velocity was bigger than the grain growing velocity in this stage. When the ball milling time was beyond 9 h, the average grain size reached a steady minimum value about 27.5 nm. The microhardness of BNC-Cu samples increased with the extending of ball milling time in the first 9 h because the dominating factor was the hardening effect caused by grain refinement and work hardening rather than softening in this stage. BNC-Cu gained its highest microhardness about 1.59GPa when the ball milling time reached 9 h. Subsequently, the microhardness of BNC-Cu slightly fluctuated around this value. Because there were numerous triple grain boundaries and the interaction among different crystal defects in BNC-Cu, BNC-Cu showed outstanding thermal stability when it was annealed in the range of 100°C to 400°C.

scholarly journals Microstructure and Mechanical Properties of Nanocrystalline Al-Zn-Mg-Cu Alloy Prepared by Mechanical Alloying and Spark Plasma Sintering

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1255 ◽  
Author(s):  
Cheng ◽  
Cai ◽  
Zhao ◽  
Yang ◽  
Chen ◽  
...  
Keyword(s):  
Grain Size ◽  
Ball Milling ◽  
Spark Plasma Sintering ◽  
Milling Time ◽  
Milled Powder ◽  
Bulk Alloy ◽  
Engineering Strain ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Ball Milling Time

In this study, Al, Zn, Mg and Cu elemental metal powders were chosen as the raw powders. The nanocrystalline Al-7Zn-2.5Mg-2.5Cu bulk alloy was prepared by mechanical alloying and spark plasma sintering. The effect of milling time on the morphology and crystal structure was investigated, as well as the microstructure and mechanical properties of the sintered samples. The results show that Zn, Mg and Cu alloy elements gradually dissolved in α-Al with the extension of ball milling time. The morphology of the ball-milled Al powder exhibited flaking, crushing and welding. When the ball milling time was 30 h, the powder particle size was 2–5 μm. The α-Al grain size was 23.2 nm. The lattice distortion was 0.156% causing by the solid solution of the metal atoms. The grain size of ball-milled powder grew during the spark plasma sintering process. The grain size of α-Al increased from 23.2 nm in the powder to 53.5 nm in the sintered sample during the sintering process after 30 h of ball milling. At the same time, the bulk alloy precipitated micron-sized Al2Cu and nano-sized MgZn2 in the α-Al crystal. With the extension of ball milling time, the compression strength, yield strength and Vickers hardness of spark plasma sintering (SPS) samples increased, while the engineering strain decreased. The compression strength, engineering strain and Vickers hardness of sintered samples prepared by 30 h milled powder were ~908 MPa, ~8.1% and ~235 HV, respectively. The high strength of the nanocrystalline Al-7Zn-2.5Mg-2.5Cu bulk alloy was attributed to fine-grained strengthening, dislocation strengthening and Orowan strengthening due to the precipitated second phase particles.

Effect of High-Energy Ball-Milling and TiB2 Content on Microstructures and Properties of Cu-TiB2 Composites Sintered by SPS

2006 ◽  
Vol 118 ◽  
pp. 661-665 ◽  
Author(s):  
Dae Hwan Kwon ◽  
Thuy Dang Nguyen ◽  
Pyuck Pa Choi ◽  
Ji Soon Kim ◽  
Young Soon Kwon
Keyword(s):  
Electrical Conductivity ◽  
Ball Milling ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball ◽  
Xrd Patterns ◽  
Short Time ◽  
Tib2 Particles

The microstructure and properties of Cu-TiB2 composites produced by high-energy ball-milling of TiB2 powders and spark-plasma sintering (SPS) were investigated. TiB2 powders were mechanically milled at a rotation speed of 1000rpm for short time in Ar atmosphere, using a planetary ball mill. To produce Cu-xTiB2 composites( x = 2.5, 5, 7.5 and 10wt.% ), the raw and milled TiB2 powders were mixed with Cu powders by means of a turbular mixer, respectively. Sintering of mixed powders was carried out in a SPS facility under vacuum. High-energy ball-milling resulted in refinement of TiB2 particles. XRD patterns of milled TiB2 powders indicated broader TiB2 peaks with decreased intensities. After sintering at 950 for 5min using the raw and milled TiB2 mixture powders, the sintered density decreased with increasing TiB2 content regardless of milling of TiB2. In the case of raw TiB2, hardness rapidly increased from 4 to 44 HRB with increasing TiB2 content. The electrical conductivity changed from 95.5 to 80.7 %IACS. For mixtures of Cu powders with milled TiB2 powders, hardness increased from 38 to 67 HRB as TiB2 content increased, while the electrical conductivity varied from 88% to 51 % IACS. When compared to compacts sintered with raw and milled TiB2 powders, the electrical conductivity of specimens with raw TiB2 powder was higher than that of specimens with milled TiB2 powder, while hardness was slightly lower.

Al-SiC Nanocomposites Produced by Ball Milling and Spark Plasma Sintering

2013 ◽  
Vol 1513 ◽  
Author(s):  
R.C. Picu ◽  
J.J. Gracio ◽  
G.T. Vincze ◽  
N. Mathew ◽  
T. Schubert ◽  
...  
Keyword(s):  
Yield Stress ◽  
Ball Milling ◽  
Spark Plasma Sintering ◽  
High Energy ◽  
Sic Nanoparticles ◽  
Sic Particles ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball ◽  
Annealing Experiments

ABSTRACTIn this work Al-SiC nanocomposites were prepared by high energy ball milling followed by spark plasma sintering of the powder. For this purpose Al micro-powder was mixed with 50 nm diameter SiC nanoparticles. The final composites had grains of approximately 100 nm dimensions, with SiC particles located mostly at grain boundaries. To characterize their mechanical behavior, uniaxial compression, micro- and nano-indentation were performed. Materials with 1vol% SiC as well as nanocrystalline Al produced by the same means with the composite were processed, tested and compared. AA1050 was also considered for reference. It was concluded that the yield stress of the nanocomposite with 1 vol% SiC is 10 times larger than that of regular pure Al (AA1050). Nanocrystalline Al without SiC and processed by the same method has a yield stress 7 times larger than AA1050. Therefore, the largest increase is due to the formation of nanograins, with the SiC particles’ role being primarily that of stabilizing the grains. This was demonstrated by performing annealing experiments at 150°C and 250°C for 2h, in separate experiments.

Nickel/Alumina Metal Matrix Nanocomposites Obtained by High-Energy Ball Milling and Spark Plasma Sintering

2018 ◽  
Author(s):  
Enrique Martínez-Franco ◽  
Ming Li ◽  
Ricardo Cuenca Álvarez ◽  
Jesús González Hernández ◽  
Chao Ma ◽  
...  
Keyword(s):  
Ball Milling ◽  
Spark Plasma Sintering ◽  
Metal Matrix ◽  
High Energy ◽  
Alumina Nanoparticles ◽  
Metal Matrix Nanocomposites ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball ◽  
Matrix Nanocomposites

Metal matrix nanocomposites (MMNCs) are anticipated to offer significantly better performance than existing superalloys. Nickel/alumina nanocomposite samples were fabricated with a powder metallurgy method, combining high-energy ball milling (HEBM) and spark plasma sintering (SPS). The objective of this research is to determine the effect of alumina nanoparticle fraction and HEBM parameters on the powder preparation and sintering processes, and resultant microstructure and properties. Nickel-based powders containing various fractions (1, 5 and 15 vol.%) alumina nanoparticles were prepared by HEBM. The initial particle sizes were 44 μm and 50 nm for nickel and alumina, respectively. The milling process was conducted by starting with mixing at 250 rpm for 5 min, followed by cycling operation at high and low speeds (1200 rpm for 4 min and 150 rpm for 1 min). Samples at different milling times (30, 60, 90 and 120 min) of each composition were obtained. Scanning electron microscopy (SEM) was used to evaluate the dispersion of nanoparticles in the powders at different milling times. SPS technique was used for consolidation of the prepared powders. SEM images showed that alumina nanoparticles are homogeneously dispersed in the metal matrix in the sample containing 15 vol.% alumina. Hardness measurements in cross sections of SPSed samples showed higher values for Ni/Al2O3 MMNC compared to pure Ni.

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