scholarly journals SYNTHESIS AND CHARACTERIZATION OF TiB2 NANOCRYSTALLINE POWDER BY MECHANICAL ALLOYING

2012 ◽  
Vol 05 ◽  
pp. 204-211 ◽  
Author(s):  
MAHBOOBEH MOALLEM ◽  
MOHAMMAD HASAN ABBASI ◽  
FATHOLLAH KARIM ZADEH
Keyword(s):  
Grain Size ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Lattice Strain ◽  
Structural Evolution ◽  
Nanocrystalline Powder ◽  
Combustion Mechanism ◽  
Mechanically Alloyed ◽  
Xrd Patterns

In this investigation, TiB 2 nanocrystalline powder was synthesized by mechanical alloying of the elemental mixture of Ti and B powders in argon atmosphere. In order to study the structural evolution of the powder during ball milling, X-Ray diffraction (XRD) and scanning electron microscopy (SEM) were used. Adiabatic temperature calculations were performed for characterization of TiB 2 powder. Also, the effects of heat treatment on the structural evolution and thermal stability of mechanically alloyed powders were investigated. It was found from the XRD patterns that TiB 2 was formed via combustion mechanism. By increasing milling time, the grain size decreased while the lattice strain increased. SEM micrographs showed that TiB 2 particles were spherical. The grain size and lattice strain reached 24 nm and 1.8% respectively, after 60 hours ball milling.

Characterization of Cold-Sprayed FeAl/WC Nanocomposite Coating

2013 ◽  
Vol 423-426 ◽  
pp. 63-66
Author(s):  
Hong Tao Wang ◽  
Ruo Yu Wang ◽  
Xiao Chen ◽  
Xiao Bo Bai ◽  
Zeng Xiang Dong ◽  
...  
Keyword(s):  
Grain Size ◽  
Lamellar Structure ◽  
Annealing Temperature ◽  
Annealing Treatment ◽  
Cold Spraying ◽  
Nanocomposite Coating ◽  
Mechanically Alloyed ◽  
Dense Microstructure ◽  
Before And After

A FeAl/WC nanocomposite coating was produced by cold spraying of mechanically alloyed Fe/Al/WC composite powder assisted with annealing treatment. The microstructure and grain size of FeAl/WC nanocomposite coating before and after annealing treatment were characterized. The results indicated that as-sprayed Fe (Al)/WC nanocomposite coating presented a dense microstructure with lamellar structure. The phase transformation from Fe (Al) solid solution to FeAl intermetallics within as-sprayed nanocomposite coating occurred when annealed at 550°C for 25 h. The annealed nanocomposite coating was composed of nanograins of size ranging from 50-100 nm and the grain size of FeAl increased with increasing the annealing time. Moreover, the effect of annealing temperature on the microstructure of the FeAl/WC nanocomposite coating was investigated.

Nickel Silicides Synthesized by High Energy Ball Milling

2007 ◽  
Vol 353-358 ◽  
pp. 1625-1628 ◽  
Author(s):  
Gen Shun Ji ◽  
Qin Ma ◽  
Tie Ming Guo ◽  
Qi Zhou ◽  
Jian Gang Jia ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
Planetary Mill ◽  
High Energy Ball Milling ◽  
X Ray Diffraction ◽  
Microstructure Morphology ◽  
Energy Ball ◽  
Xrd Patterns

The high energy ball milling of Ni-50 atom % Si elemental powder mixtures was carried out using a planetary mill. X-ray diffraction (XRD) was used to identify the phase evolutions during the high energy ball milling period. The microstructure morphology of the powders milled different time was determined by field emission scanning electron microscope (FESEM). The beginning time of mechanical alloying was determined by back scattered electrons (BSE) images. The XRD patterns showed that the nickel peaks intensity and the silicon peaks intensity obviously decreased with milling time increased to 1 hour. BSE images revealed that nickel and silicon powders were not blended uniformly for 1 hour of milling. It was found that NiSi formed as the milling time increased to 5 hours, simultaneously, the nickel peaks and the silicon peaks almost disappeared. That means the obvious mechanical alloying started from 5 hours of milling. BSE images agreed with the result analyzed from XRD patterns. With the milling time further increased from 10 to 75 hours, the NiSi peaks decreased gradually, at the same time, the Ni2Si peaks appeared and then increased gradually.

scholarly journals THE INFLUENCE OF MECHANICALLY ALLOYED MODIFYING MASTER LIGATURES ON STRUCTURE AND PROPERTIES OF WELDED JOINTS

2018 ◽  
pp. 102-108
Author(s):  
F. G. Lovshenko ◽  
G. F. Lovshenko ◽  
A. I. Khabibulin
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Mechanical Alloying ◽  
Weld Metal ◽  
Welded Joints ◽  
Dispersion Hardening ◽  
Structure And Properties ◽  
Mechanically Alloyed ◽  
Actual Problem ◽  
Effective Technology

Actual problem of modern welding production is the creation of electrodes for maximum performance and efficiency of the process whithin the required reliability and durability of the structure. A promising way to improve mechanical properties of the weld metal is the implementation of the mechanism of dispersion hardening. Reactionary mechanical alloying is an effective technology of obtaining nanocrystalline modifying ligatures and modifiers. The use of electrodes with an experimental coating containing a mechanically alloyed, composite ligature to resolve transcrystalline type of structure of the weld metal and reduce the grain size by 2.5–3.0 times (from # 8–9 to #11–12) reduces by 20–30% the threshold of cold brittleness and increase by 15– 25% of the mechanical properties of the weld metal.

scholarly journals Generation, structure and properties of the modified welding seams

2018 ◽  
pp. 131-140
Author(s):  
F. G. Lovshenko ◽  
A. I. Khabibulin
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Mechanical Alloying ◽  
Weld Metal ◽  
Cold Brittleness ◽  
Structure And Properties ◽  
Mechanically Alloyed ◽  
Aluminum Oxides ◽  
Generation Structure ◽  
Effective Technology

Preparation, structure and properties of modified welds by using electrodes with coatings, which contain, along with classical components, a modifying ligature. The ligature is mechanically and thermally synthesized composite submicrocrystalline powders with nanosized inclusions of aluminum oxides. Reactionary mechanical alloying is an effective technology of obtaining nanocrystalline modifying ligatures and modifiers. The use of electrodes with an experimental coating containing a mechanically alloyed, composite ligature to resolve transcrystalline type of structure of the weld metal and reduce the grain size by 2,5–3,0 times (from № 8–9 to № 11–12) reduces by 20–30% the threshold of cold brittleness and increase by 15–25% of mechanical properties of the weld metal.

scholarly journals Synthesis and Characterization of Nanocrystalline Ni50Al50−xMox (x = 0–5) Intermetallic Compound during Mechanical Alloying Process

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
A. Khajesarvi ◽  
G. H. Akbari
Keyword(s):  
Intermetallic Compound ◽  
Mechanical Alloying ◽  
Lattice Strain ◽  
Atomic Percent ◽  
Synthesis And Characterization ◽  
Nickel Aluminum ◽  
X Ray ◽  
Average Grain Size ◽  
Scanning Electron

Nanocrystalline Ni50Al50-xMox (x=0, 0.5, 1, 2.5, 5) intermetallic compound was produced through mechanical alloying of nickel, aluminum, and molybdenum powders. Powders produced from milling were analyzed using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Results showed that, with increasing the atomic percent of molybdenum, average grain size decreased from 3 to 0.5 μm. Parameter lattice and lattice strain increased with increasing the atomic percent of molybdenum, while the crystal structure became finer up to 10 nm. Also, maximum microhardness was obtained for NiAl49Mo1 alloy.

Synthesis And Characterization Of Ball-Milled Nanocrystalline Fcc Metals

1991 ◽  
Vol 238 ◽  
Author(s):  
J. Eckert ◽  
J. C. Holzer ◽  
C. E. Krill ◽  
W. L. Johnson
Keyword(s):  
Grain Size ◽  
Melting Point ◽  
Grain Boundary ◽  
Bulk Modulus ◽  
Ball Milling ◽  
Lattice Strain ◽  
Boundary Migration ◽  
General Relation ◽  
Heat Of Fusion ◽  
Scanning Calorimetry

ABSTRACTNanocrystalline fee metals (Al, Cu, Ni, Pd, Rh, Ir) have been prepared by ball milling. The development of the microstructure is investigated by x-ray diffraction, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The final grain sizes range from 6 to 22 nm and scale with the melting point and the bulk modulus of the elements: metals with higher melting point and bulk modulus have a smaller final grain size. From this a general relation between the deformation mechanism during ball milling and the ultimate grain size achievable by this technique is inferred. With decreasing grain size the lattice strain is enhanced and deformation enthalpies of up to 40 % of the heat of fusion are stored in the material. The contributions of the lattice strain and of die excess enthalpy of the grain boundaries to the stored enthalpies are critically assessed. The kinetics of grain growth are investigated by mermal analysis. The activation energy for grain boundary migration is derived from a modified Kissinger analysis and estimates of the grain boundary enthalpy are given.

FABRICATION AND CHARACTERIZATION OF NANOSTRUCTURED CU-15WT.% MO COMPOUND BY MECHANICAL ALLOYING

2012 ◽  
Vol 05 ◽  
pp. 456-463
Author(s):  
Soheil Sabooni ◽  
Tayebeh Mousavi ◽  
Fathallah Karimzadeh
Keyword(s):  
Solid Solution ◽  
Mechanical Alloying ◽  
Structural Evolution ◽  
Weight Percent ◽  
Chromium Steel ◽  
X Ray Diffraction ◽  
Milling Operation ◽  
Powder Particles ◽  
Solid Solution Matrix

In the present study nanostructured Cu ( Mo ) compound with 15 weight percent Mo was produced by mechanical alloying using a planetary ball mill. The milling operation was carried out in hardened chromium steel vial and balls under argon atmosphere with a constant ball to powder ratio of 10:1. The structural evolution and characterization of powder particles after different milling times were studied by X-Ray Diffraction, SEM observation and Microhardness measurements. The results showed the displacement of broadened Cu peaks to lower angles, because of dissolving Mo in Cu . The final product was a nanocomposite contains nanocrystalline Cu ( Mo ) supersaturated solid solution matrix and dispersion of nanometric Mo reinforcements. The microhardness of formed nanocomposite increased to 350HV because of grain refinement, formation of solid solution and dispersion hardening.

HEAT TREATMENT EFFECTS ON STRUCTURE AND PROPERTIES OF SYNTHESIZED NANOCRYSTALLINE NiTi INTERMETALLIC BY MECHANICAL ALLOYING

2008 ◽  
Vol 22 (18n19) ◽  
pp. 2970-2978
Author(s):  
T. MOUSAVI ◽  
M. H. ABBASI ◽  
F. KARIMZADEH ◽  
M. H. ENAYATI
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Mechanical Alloying ◽  
Lattice Strain ◽  
Metastable Phase ◽  
Nanocrystalline Structure ◽  
X Ray Diffraction ◽  
Niti Phase ◽  
High Microhardness ◽  
The Right

NiTi intermetallic with nanocrystalline structure was produced by mechanical alloying of the elemental powders and the effect of subsequent heat treatment was investigated. The products were characterized using X-ray diffraction and microhardness measurements. The results showed that after 60 h of mechanical alloying, disordered B 2- NiTi phase can be obtained as a metastable phase at room temperature with grain size of 25 nm, lattice strain and high microhardness of 1.2% and 922 HV, respectively. After heat treatment, disordered structure transformed to ordered NiTi and a small amount of NiTi 2 and Ni 3 Ti phases. The long range order parameters of nanocrystalline NiTi were obtained to be 0.63 and 0.94 after annealing for 30 and 60 mins respectively. After 30 mins of heat treatment, 81.5% of Ni (or Ti ) atoms were on the right sites and after 60 mins it increased to 97%. Grain growth and decrease of microhardness and lattice strain were also observed after heat treatment. After 60 mins of heat treatment the grain size, lattice strain and microhardness of NiTi were 95, 0.09 and 624 HV respectively.

THE EFFECT OF Mn ON α TO γ TRANSFORMATION IN THE NANOSTRUCTURED HIGH NITROGEN Fe-Cr-Mn STAINLESS STEEL PRODUCED BY MECHANICAL ALLOYING

2012 ◽  
Vol 05 ◽  
pp. 49-57
Author(s):  
FARIBA TEHRANI ◽  
MOHAMMAD HASAN ABBASI ◽  
MOHAMMAD ALI GOLOZAR ◽  
MASOUD PANJEPOUR
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Mechanical Alloying ◽  
Milling Time ◽  
High Energy ◽  
Nitrogen Atmosphere ◽  
Transformation Rate ◽  
X Ray Diffraction ◽  
High Nitrogen ◽  
Xrd Patterns

In this study, the effect of Mn on α to γ transformation in the nanostructured high nitrogen Fe -18 Cr - xMn stainless steel produced by mechanical alloying (MA) was investigated. MA was performed under nitrogen atmosphere using a high-energy planetary ball mill. X- ray diffraction (XRD) patterns of produced samples showed that α to γ transformation starts after 20 hours of milling and propagates by increasing the milling time. Completion of this phase transformation occurred in the Fe -18 Cr -8 Mn sample after 100 hours of milling. But, in the Fe -18 Cr -7 Mn sample, some α phase remained even after 150 hours of milling. Also, nitrogen analysis revealed that nitrogen solubility in the milled powders increased significantly by increasing the milling time, and ultimately reached 1wt%. This is believed to be due to the increase of the lattice defects and development of nanostructure through MA. Variations in grain size and internal lattice strain versus milling time in both cases showed that the critical ferrite grain size for austenite nucleation was lower than 10nm. Moreover, a lower transformation rate was found in samples containing lower Mn content.

Phase selection in a mechanically alloyed Cu2013;In–Ga–Se powder mixture

1999 ◽  
Vol 14 (2) ◽  
pp. 377-383 ◽  
Author(s):  
C. Suryanarayana ◽  
E. Ivanov ◽  
R. Noufi ◽  
M. A. Contreras ◽  
J.J. Moore
Keyword(s):  
Grain Size ◽  
Hot Isostatic Pressing ◽  
Structural Evolution ◽  
Full Density ◽  
Alloyed Powder ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Phase Selection ◽  
Blended Elemental ◽  
Transmission Electron

Formation of a homogeneous nanocrystalline CuIn0.7Ga0.3Se2 alloy was achieved by mechanical alloying of blended elemental Cu, In, Ga, and Se powders in a planetary ball mill. X-ray diffraction and transmission electron microscopy and diffraction techniques were employed to follow the structural evolution during milling. It was observed that, depending upon the milling conditions, either a metastable cubic or a stable tetragonal phase was produced. The grain size of the mechanically alloyed powder was about 10 nm. The mechanically alloyed powder was consolidated to full density by hot isostatic pressing the powder at 750 °C and 100 MPa for 2 h. Irrespective of the nature of the phase in the starting powder, the hot isostatically pressed compact contained the well-recrystallized tetragonal CuIn0.7Ga0.3Se2 phase with a grain size of about 50 nm.

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