Decomposition and Crystallization Induced by High-Energy Ball-Milling

2007 ◽  
Vol 119 ◽  
pp. 1-4 ◽  
Author(s):  
Young Soon Kwon ◽  
Ji Soon Kim ◽  
Cheol Eeh Kim
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
Thermally Induced ◽  
Average Grain Size ◽  
Powder Particles ◽  
Energy Ball ◽  
Decomposition Behavior

Phase transformation induced by ball-milling was studied in this work. It was found that amorphous Fe90Zr10 ribbons undergo crystallization into BCC α-Fe(Zr) under milling in an AGO-2 mill. The decomposition degree of the amorphous phase increased with increasing milling time and intensity. Analyses of samples milled at different speeds suggested that the observed crystallization is a deformation-induced process rather than a thermally induced one. In addition, the decomposition behavior of a FeSn intermetallic under ball-milling was carefully studied. Upon milling a large amount of the FeSn intermetallic decomposed into Fe5Sn3 and FeSn2, where the average grain size of the product phases stayed nearly constant with milling-time. It is suggested that the mechanically driven decomposition of FeSn results from local melting of powder particles due to high temperature pulses during ball collisions.

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.

Preparation of WC-5TiC-10Co Nanometer Powder and Performance Study of Sintering Samples

2012 ◽  
Vol 465 ◽  
pp. 220-223 ◽  
Author(s):  
Chong Cai Zhang ◽  
Quan Wang ◽  
Qun Qun Yuan ◽  
Yong Fei Yang ◽  
Xiao Lan Yi
Keyword(s):  
Grain Size ◽  
Compressive Strength ◽  
Ball Milling ◽  
High Energy ◽  
Cemented Carbides ◽  
Performance Study ◽  
Vacuum Sintering ◽  
Average Grain Size ◽  
Energy Ball ◽  
And Performance

In this paper, the WC-5TiC-10 Co mixture mixed by WC2.96μm, (Ti, W)C 2.52μm and Co2.38μm and prepared by high-energy ball milling. The result shows: After 60h’s ball milling the powder began to reunite more and more as the time extended . The average grain size of powder is 50 nm after144h. After 1300°C~1400°C vacuum-sintering the hardness of the sample is 94.8 ~ 95.4HRA. 4.2 ~ 5.2 HRA higher than the traditional cemented carbides with the same composition. After 1400°C vacuum-sintering the compressive strength and flexural strength of cemented carbides is 2060 MPa and 1200 MPa. Slightly less than the traditional cemented carbides with the same composition.

Nanocrystalline Cu90Nb10 Alloy Produced by Mechanical Alloying

2013 ◽  
Vol 750-752 ◽  
pp. 752-755
Author(s):  
C.J. Li ◽  
Q.X. Zhang ◽  
Q. Yuan ◽  
J. Tan ◽  
L. Teng ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
Deformation Degree ◽  
Solid Solution Strengthening ◽  
Fine Grain ◽  
Powder Particles ◽  
Energy Ball ◽  
Ball Milling Time

Nanocrystalline Cu90Nb10 alloy was produced by high energy ball milling mechanical alloying (MA). The effects of ball milling time on the microstructure and mechanical property of this alloy in the process of MA were investigated. The results show: up to 10 at.% Nb could be dissolved into Cu matrix by MA; the powder particles became compacted and homogeneous with increasing the ball milling time, and the deformation degree also increased synchronously; the grain size of this alloy was refined gradually, and it reached the minimum value of 11.5 nm after 30h milling; the microhardness of this alloy increased with increasing the milling time, and it obtained the maximum value of 328 Hv after 30h milling. The obvious reinforcement of this alloy may be due to the comprehensive effects of the fine grain strengthening, the solid solution strengthening and the strain strengthening.

Mechanical Alloying of Al2O3-Co Powders Mixture

2006 ◽  
Vol 306-308 ◽  
pp. 1109-1114 ◽  
Author(s):  
W.S. Yeo ◽  
Iskandar Idris Yaacob
Keyword(s):  
Phase Transformation ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
X Ray ◽  
Hexagonal Close Packed ◽  
Nominal Size ◽  
Alumina Particles ◽  
Energy Ball ◽  
Ball Milling Technique

Nanocomposite Al2O3-Co was prepared by high-energy ball milling technique. Nanoscaled alumina particles (γ-Al2O3) of 5wt% with nominal size 39 nm were dispersed in cobalt matrix. The phase transformation of the element occurs in the powders mixture during the process was monitored by X-ray diffractometry (XRD). The results showed that cobalt exhibits phase transformation when subjected to ball milling. The phase formation of cobalt was found to depend on the milling intensity. As the milling time increased, the amount of the hexagonal close-packed (hcp) phase decreased.

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.

Microstructure and Characteristics of Ti-Nb-Sn-HA Composite Powder Fabricated by Mechanical Alloying

2011 ◽  
Vol 55-57 ◽  
pp. 886-891
Author(s):  
Xiao Peng Wang ◽  
Shu Long Xiao ◽  
Yu Yong Chen ◽  
Zhi Guang Liu ◽  
Kee Do Woo
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Milled Powder ◽  
High Energy ◽  
Composite Powders ◽  
Β Phase ◽  
Α Phase ◽  
High Energy Ball Mill ◽  
Powder Particles ◽  
Energy Ball

A novel biocomposite Ti-35wt%Nb-2.5wt%Sn-15wt%HA powders was synthesized by high energy ball mill(HEBM) for various periods of time. The microstructure and characteristics of the milled powder particles were investigated. Results showed that in the composite powders milled for 4h, Ti was still exhibited primary α phase, with the increase of ball milling time up to 8h, Ti transformed into primary β phase and a little α phase, after ball milling for 12h, Ti transformed into β phase fully. the transform temperature was 380.06°C. And TEM and PSD results indicated that nanostructure was obtained after 12h milling..

Synthesis of Ag-Cu-Sn Nanocrystalline Alloys as Intermediate Temperature Solder by High Energy Ball Milling

2009 ◽  
Vol 79-82 ◽  
pp. 449-452 ◽  
Author(s):  
Liang Feng Li ◽  
Tai Qiu ◽  
Jian Yang ◽  
Yong Bao Feng
Keyword(s):  
Grain Size ◽  
Ball Milling ◽  
High Energy ◽  
Nanocrystalline Alloys ◽  
High Energy Ball Milling ◽  
Intermediate Temperature ◽  
Melting Points ◽  
Small Particles ◽  
Average Grain Size ◽  
Energy Ball

To obtain intermediate temperature alloy solders with melting temperature of 400~600°C, (Ag-Cu28)-25Sn and (Ag-Cu28)-30Sn alloys were prepared by high energy ball milling. Ag-Cu-Sn nanocrystalline alloys have been obtained after milling for 40h. XRD results show that the (Ag-Cu28)-25Sn alloy consists of Ag4Sn and Cu3Sn, and the (Ag-Cu28)-30Sn alloy contains Ag4Sn, Cu3Sn and Cu6Sn5. The small polydispersed particles with size ranging from 1μm to about 25μm are observed from the (Ag-Cu28)-30Sn alloys milled for 40h by SEM. A large amount of small particles comprised of two or three grains are commonly observed by HRTEM, and average grain size is about 17.50nm. DSC results indicate that the melting points of the (Ag-Cu28)-25Sn and (Ag-Cu28)-30Sn alloys milled for 40h are 548.5°C and 539.3°C, respectively.

Preparation of Cu-Zn Alloy by Different High Energy Ball Milling

2011 ◽  
Vol 412 ◽  
pp. 259-262
Author(s):  
Kai Jun Wang ◽  
Xiao Lan Cai ◽  
Hua Wang ◽  
Jin Hu ◽  
Yun Feng Zhang
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Attrition Mill ◽  
Phase Form ◽  
Elemental Copper ◽  
Energy Ball ◽  
New Phase ◽  
Zn Alloy

Cu-Zn alloy was prepared by high energy ball milling of elemental copper and zinc by the Simoloyer attrition mill, the different parameters such as milling time, ball-to-powder ratio and rotational speeds were analyzed. The results show that the different Cu-Zn alloy phase can be produced by different ball milling parameters, It has been found that milling time is highly significant to refining process, and the ratios of ball to powder are also benefited to the new phase form.

Development of Ni/h-BN Self-Lubricating Composite Powder by High-Energy Ball Milling

2016 ◽  
Vol 869 ◽  
pp. 277-282
Author(s):  
Moisés Luiz Parucker ◽  
César Edil da Costa ◽  
Viviane Lilian Soethe
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Solid Lubricants ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Second Phase ◽  
Average Particle ◽  
Composite Powders ◽  
The Matrix ◽  
Energy Ball

Solid lubricants have had good acceptance when used in problem areas where the conventional lubricants cannot be applied: under extreme temperatures, high charges and in chemically reactive environments. In case of materials manufactured by powder metallurgy, particles of solid lubricants powders can be easily incorporated to the matrix volume at the mixing stage. In operation, this kind of material provides a thin layer of lubricant that prevents direct contact between the surfaces. The present study aimed at incorporating particles of second phase lubricant (h-BN) into a matrix of nickel by high-energy ball milling in order to obtain a self-lubricating composite with homogeneous phase distribution of lubricant in the matrix. Mixtures with 10 vol.% of h-BN varying the milling time of 5, 10, 15 and 20 hours and their relationship ball/powder of 20:1 were performed. The effect of milling time on the morphology and microstructure of the powders was studied by X-ray diffraction, SEM and EDS. The composite powders showed reduction in average particle size with increasing milling time and the milling higher than 5 hours resulted in equiaxial particles and the formation of nickel boride.

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