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.

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.

Synthesis of High Nitrogen Stainless Steel Powders by High Energy Ball Milling and their SPS Compaction

2010 ◽  
Vol 97-101 ◽  
pp. 1142-1145
Author(s):  
Da Wei Cui ◽  
Jin Long Wang
Keyword(s):  
Stainless Steel ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
Nitrogen Atmosphere ◽  
High Energy Ball Milling ◽  
High Nitrogen ◽  
Particle Size Range ◽  
Energy Ball ◽  
High Nitrogen Stainless Steel

High nitrogen nanostructured Fe-17Cr-11Mn-3Mo stainless steel powders were produced by high energy ball milling under a nitrogen atmosphere. It was found with increasing the milling time, the nitrogen contents of the powder mixtures increase linearly up to 1.98 wt pct after 96h, and a linear regression equation, WN = 0.19357 + 0.01887t , has been further established. In addition, with the increased milling time, the crystallite sizes and particle sizes of the powders decrease continuously, the lattice strains and sphericity of the powders increase gradually. After milling 60h, the high nitrogen nanocrystalline stainless steel powders with a fine particle size range of 5~10μm, excellent sphericity and uniform components can be obtained, whose crystallite size is about 5.0nm and lattice strain is about 1.0%. The powders milled for 60h was compacted using spark plasma sintering process at different temperatures. It is found that a fully austenitic high nitrogen stainless steel with almost full densification can be obtained by SPS at 1000°C, whose nitrogen content is 0.82 wt pct.

Effects of Ball Milling Time on the Microstructure and Mechanical Property of Cu90Al10 Alloy

2013 ◽  
Vol 750-752 ◽  
pp. 663-666
Author(s):  
C.J. Li ◽  
G. Chen ◽  
Q. Yuan ◽  
J. Tan ◽  
L. Teng ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Grain Size ◽  
Yield Strength ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Milling Time ◽  
Structural Characteristics ◽  
High Energy ◽  
Powder Particle Size ◽  
X Ray Diffraction

Nanostructured Cu90Al10 alloy powders were prepared by high energy ball milling mechanical alloying (MA). Up to 10 at.% Al could be dissolved into copper by mechanical alloying at room temperature. Effects of milling time on phase transformation, structural characteristics, and mechanical property of powders were investigated by using X-ray diffraction (XRD), Optical Microscopy (OM) and microhardness tester. The results show: with increasing the milling time, the powder particle size increased gradually, and then it tended to be homogeneous. The grain size of the alloy decreased gradually, but the yield strength increased with the extension of the ball milling. After 30h milling, the grain size reached the minimum value of 9 nm, and the yield strength obtained the maximum value of 511 MPa.

The Synthesis of Cu0.81Ni0.19 Intermetallics by Mechanical Alloying

2012 ◽  
Vol 496 ◽  
pp. 379-382
Author(s):  
Rui Song Yang ◽  
Ming Tian Li ◽  
Chun Hai Liu ◽  
Xue Jun Cui ◽  
Yong Zhong Jin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Grain Size ◽  
Mechanical Alloying ◽  
Milling Time ◽  
Elemental Powder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scherrer Equation ◽  
Scanning Electron

The Cu0.81Ni0.19 has been synthesized directly from elemental powder of nickel and copper by mechanical alloying. The alloyed Cu0.81Ni0.19 alloy powders are prepared by milling of 8h. The grain size calculated by Scherrer equation of the NiCu alloy decreased with the increasing of milling time. The end-product was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM)

Appropriate Conditions for Preparation of Nanosized WO3 through High-Energy-Milling

2011 ◽  
Vol 194-196 ◽  
pp. 665-668
Author(s):  
Chun Huan Chen ◽  
Rui Ming Ren
Keyword(s):  
Grain Size ◽  
Milling Time ◽  
Rotation Speed ◽  
Processing Parameters ◽  
High Energy ◽  
Charge Ratio ◽  
Activation Process ◽  
X Ray Diffraction ◽  
High Energy Milling ◽  
Transmission Electron

In order to synthesize WC-Co nanopowders through an integrated mechanical and thermal activation process, WO3-Co2O3-C nanopowders need to be obtained first. It is critical how to obtain the WO3-Co2O3-C nanopowders efficiently. The effect of processing parameters on the grain size during high-energy-milling of WO3-Co2O3-C mixed powders was studied via X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the grain size of reactants can be effectively decreased with increasing the milling time, rotation speed, and charge ratio. After a certain time milling, both WO3 and C powders achieve nano-level in grain size and mixed homogeneously. The appropriate milling parameters for fabricating nanosized WO3+C+Co2O3 powders are suggested to be 4 to 8 hours of milling time, 400 RPM of rotation speed, and 40:1 to 60:1 of charge ratio.

Effect of Milling Speed on the Synthesis of In-Situ Cu-25 Vol. % WC Nanocomposite by Mechanical Alloying

2012 ◽  
Vol 59 (2) ◽  
Author(s):  
Nurulhuda Bashirom ◽  
Nurzatil Ismah Mohd Arif
Keyword(s):  
Stainless Steel ◽  
Mechanical Alloying ◽  
Weight Ratio ◽  
High Energy ◽  
Milling Process ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
The Matrix ◽  
Steel Balls

This paper presents a study on the effect of milling speed on the synthesis of Cu-WC nanocomposites by mechanical alloying (MA). The Cu-WC nanocomposite with nominal composition of 25 vol.% of WC was produced in-situ via MA from elemental powders of copper (Cu), tungsten (W), and graphite (C). These powders were milled in the high-energy “Pulverisette 6” planetary ball mill according to composition Cu-34.90 wt% W-2.28 wt% C. The powders were milled in different milling speed; 400 rpm, 500 rpm, and 600 rpm. The milling process was conducted under argon atmosphere by using a stainless steel vial and 10 mm diameter of stainless steel balls, with ball-to-powder weight ratio (BPR) 10:1. The as-milled powders were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). XRD result showed the formation of W2C phase after milling for 400 rpm and as the speed increased, the peak was broadened. No WC phase was detected after milling. Increasing the milling speed resulted in smaller crystallite size of Cu and proven to be in nanosized. Based on SEM result, higher milling speed leads to the refinement of hard W particles in the Cu matrix. Up to the 600 rpm, the unreacted W particles still existed in the matrix showing 20 hours milling time was not sufficient to completely dissolve the W.

The Investigation of Structural and Magnetic Properties at High-Temperature of Nanostructured Fe90-Mg10 Alloys Produced by Mechanical Alloying

2018 ◽  
Vol 54 ◽  
pp. 136-145
Author(s):  
A. El Mohri ◽  
M. Zergoug ◽  
K. Taibi ◽  
M. Azzaz
Keyword(s):  
High Temperature ◽  
Mechanical Alloying ◽  
Milling Time ◽  
High Energy ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
High Energy Ball Mill ◽  
Energy Ball ◽  
The Mean

Nanocrystalline Fe90Mg10 alloy samples were prepared by mechanical alloying process using planetary high energy ball mill. The prepared powders were characterized using differential thermal analysis (DTA), X-ray diffraction technique (XRD) at high temperature, transmission electron microscopy (TEM), and the vibrating sample magnetometer (VSM). Obtained results are discussed according to milling time. XRD at high temperature results also indicated that when the milling time increases, the lattice parameter and the mean level of grain size increase, whereas the microstrains decrease. The result of the observation by the TEM of the Fe-Mg powders prepared in different milling time, coercive fields derived and Saturation magnetization derived from the hysteresis curves in high temperature are discussed as a function of milling time.

Morphology and Physical Studies of Nanostructured Fe64Cr36 Alloy Elaborated by Ball Milling

2013 ◽  
Vol 26 ◽  
pp. 75-81 ◽  
Author(s):  
S. Triaa ◽  
L. Faghi ◽  
F. Kali-Ali ◽  
M. Azzaz
Keyword(s):  
Milling Time ◽  
High Energy ◽  
The Body ◽  
Analysis Method ◽  
X Ray Diffraction ◽  
Bcc Structure ◽  
Iron Phase ◽  
Electron Microscopes ◽  
Xrd Patterns ◽  
Scanning Electron Microscopes

Nanostructured iron based alloy, elaborated from pure elemental powders by mechanical milling at high energy was studied. The materials obtained were characterized by several techniques, such as X-ray diffraction (XRD), which allowed the dissolution of chromium in the iron phase as a function of milling time. The peaks indicate that the obtained solid solution has the body centred cubic (bcc) structure, for a speed of 250 rpm after 24 hours milling time. The Williamson - Hall analysis method was used to exploit the recorded XRD patterns. The crystallite size of about 14 nm and the microstrain of about 0.90% were obtained for 48 hours of milling. Scanning electron microscopes (SEM) and EDX analysis have confirmed the refining of milled particles as a function of milling time and the homogenization of our powders. The measurement of reflection coefficient has revealed an increase in the microwave absorption versus milling time and has confirmed the formation of our alloy during 24 hours of milling.

Effect of Y addition on the structural transformation and thermal stability of Ti-22Al-25Nb alloy produced by mechanical alloying

2021 ◽  
Vol 63 (7) ◽  
pp. 599-605
Author(s):  
Mehmet Emin Çetin ◽  
Gökhan Polat ◽  
Mustafa Tekin ◽  
Ahmet Burçin Batibay ◽  
Hasan Kotan
Keyword(s):  
Grain Size ◽  
Mechanical Alloying ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Nanocrystalline Structure ◽  
High Energy ◽  
X Ray Diffraction ◽  
Boundary Area ◽  
Gas Atmosphere ◽  
Protective Gas

Abstract In this study, a Ti-22Al-25Nb alloy with nanocrystalline structure was produced by high energy mechanical alloying (HEMA) and 1 at.-% yttrium was added as a thermal stabilizer. The as-milled samples were annealed at various temperatures up to 900 °C in a protective gas atmosphere, and the samples were allowed to cool to room temperature in the furnace. The phase transformations and microstructural changes as a function of the annealing temperatures and alloy compositions were studied using room- and high-temperature X-ray diffraction (XRD), focused ion beam microscopy (FIB), and scanning electron microscopy (SEM). The mechanical properties of the samples were interpreted based on the hardness results and their correlation with the microstructures. The results showed that the as-milled nanocrystalline structure of Ti-22Al-25Nb alloy increased from 3.4 nm to 350 nm after annealing at 800 °C due to the high driving force induced by the large grain boundary area. Consequently, the as-milled hardness of the Ti-22Al-25Nb alloy dropped from 7.63 ± 0.18 GPa to 5.37 ± 0.28 GPa. The grain size stability of the Ti-22Al-25Nb alloy after annealing at elevated temperature was ensured through the addition of yttrium. Thus, the grain size remained at the level of 125 nm, and the hardness value was maintained at around 6.98 ± 0.43 GPa after annealing at 800 °C.

Ti-Al-Zr-B-Y Amorphous Alloy Powders Prepared by Mechanical Alloying

2015 ◽  
Vol 1095 ◽  
pp. 222-225 ◽  
Author(s):  
Yu Ying Zhu ◽  
Yun Hua He ◽  
Qiang Li
Keyword(s):  
Stainless Steel ◽  
Amorphous Alloy ◽  
Mechanical Alloying ◽  
Rotation Rate ◽  
Milling Time ◽  
High Energy ◽  
Glass Forming Ability ◽  
Argon Atmosphere ◽  
Glass Forming ◽  
Energy Ball

Mechanical alloying (MA) is used to prepare amorphous alloy powders. The experiments were performed by a high energy ball milling device using stainless steel vessels and balls under argon atmosphere at a rotation rate of 450 r/min. B and Y were used as the minor additions to prepare new quaternary or complex amorphous alloy powders. Ti50Al(47-x-y)Zr3BxYy(x=0, 0.6, y=0, 0.2) amorphous alloy powders were successively obtained. The milled amorphous alloy powders were characterized by XRD, SEM and DSC. Ti50Al47Zr3amorphous alloy powders were obtained after milled 50h. The milling time needed to obtain complete amorphous alloy for Ti50Al46.4Zr3B0.6, Ti50Al46.8Zr3Y0.2and Ti50Al46.2Zr3B0.6Y0.2are 40h, 35h and 30h, respectively. Minor additions of B and Y decreases the milling time for preparing amorphous alloy. SEM shows that B and Y can refine the grain of the amorphous alloy powders. DSC shows that minor substitution of 0.6at.%B or 0.2at.%Y can increase the glass forming ability (GFA) for the TiAl based alloys.

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