UFG to NC FePd by Combined Reaction Transformation Mode of Severely Plastically Deformed Disordered FePd

2006 ◽  
Vol 980 ◽  
Author(s):  
Vincent Sokalski ◽  
Andreas Kulovits ◽  
Jorg Wiezorek
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Phase Transformation ◽  
Cold Rolling ◽  
Grain Refinement ◽  
Magnetization Curve ◽  
Deformation Process ◽  
Intermetallic Alloys ◽  
Fine Grained ◽  
Angular Pressing

AbstractNumerous studies have shown that equiaxed ultra fine grained FePd alloys can be produced by phase transformation of heavily deformed austenitic FePd via the combined reaction mode. As the magnetic properties can be improved by suppression of the polytwinned micro-constituent formed by the conventional ordering mode it appears reasonable to speculate that further grain refinement might lead to further enhancement. In order to reduce the grain size in bulk intermetallic alloys severely plastically deformed austenitic FePd has been phase transformed in this study. Equal channel angular pressing (ECAP) has been used to deform disordered FePd. The microstructure and property evolution during the deformation process and post-deformation annealing have been studied using SEM, TEM and hardness and magnetization curve measurements. The observations are compared to known results from use of other deformation processing routes, such as cold rolling.

ULTRA FINE-GRAINED AZ31 MAGNESIUM ALLOY OBTAINED BY A COMBINATION OF GRAIN REFINEMENT AND EQUAL CHANNEL ANGULAR PRESSING

2012 ◽  
Vol 05 ◽  
pp. 307-315 ◽  
Author(s):  
S.A. TORBATI-SARRAF ◽  
R. MAHMUDI
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Grain Growth ◽  
Equal Channel Angular Pressing ◽  
Boundary Migration ◽  
Grain Refiner ◽  
Fine Grained ◽  
Angular Pressing ◽  
Grain Size Distributions

Different amounts of Al -5 Ti -1 B master alloy ( TiBAl ) were added to the AZ 31 magnesium alloy ( Mg -3 Al -1 Zn -0.2 Mn ) as grain refiner and the resulting microstructure and grain size distributions were studied after extrusion and equal channel angular pressing (ECAP). Results showed that the addition of 0.6% TiBAl had the strongest grain refinement effect, reducing the grain sizes by 54.5 and 48.5% in the extruded and ECAPed conditions, respectively. The observed grain refinement was partly due to the presence of the thermally-stable micron- and submicron-sized particles in the melt which act as nucleation sites during solidification. During the high-temperature extrusion and ECAP processes, dynamic recrystallization (DRX) and grain growth are likely to occur. However, the mentioned particles will help in reducing the grain size by the particle stimulated nucleation (PSN) mechanism. Furthermore, the pinning effect of these particles can oppose grain growth by reducing the grain boundary migration. These two phenomena together with the partitioning of the grains imposed by the severe plastic deformation in the ECAP process have all contributed to the achieved ultrafine-grained structure in the AZ 31 alloy.

scholarly journals Investigation on the Microstructure of ECAP-Processed Iron-Aluminium Alloys

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 219
Author(s):  
Bernd-Arno Behrens ◽  
Kai Brunotte ◽  
Tom Petersen ◽  
Roman Relge
Keyword(s):  
Grain Refinement ◽  
Aluminium Alloys ◽  
Aluminium Content ◽  
Microstructure Development ◽  
Chamber Furnace ◽  
Fine Grained ◽  
Angular Pressing ◽  
Ecap Process ◽  
Average Grain Size ◽  
Forming Temperature

The present work deals with adjusting a fine-grained microstructure in iron-rich iron-aluminium alloys using the ECAP-process (Equal Channel Angular Pressing). Due to the limited formability of Fe-Al alloys with increased aluminium content, high forming temperatures and low forming speeds are required. Therefore, tool temperatures above 1100 °C are permanently needed to prevent cooling of the work pieces, which makes the design of the ECAP-process challenging. For the investigation, the Fe-Al work pieces were heated to the respective hot forming temperature in a chamber furnace and then formed in the ECAP tool at a constant punch speed of 5 mm/s. Besides the chemical composition (Fe9Al, Fe28Al and Fe38Al (at.%—Al)), the influences of a subsequent heat treatment and the holding time on the microstructure development were investigated. For this purpose, the average grain size of the microstructure was measured using the AGI (Average Grain Intercept) method and correlated with the aforementioned parameters. The results show that no significant grain refinement could be achieved with the parameters used, which is largely due to the high forming temperature significantly promoting grain growth. The holding times in the examined area do not have any influence on the grain refinement.

A Study on The Phase Transformation and Exchange-Coupling of (Nd0 95La0 05)9 5FebalCo5Nb2B10.5 Nanocomposites

1999 ◽  
Vol 577 ◽  
Author(s):  
Q. Chen ◽  
B. M. Ma ◽  
B. Lu ◽  
M. Q. Huang ◽  
D. E. Laughlin
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Phase Transformation ◽  
Thermal Treatment ◽  
Grain Growth ◽  
Exchange Coupling ◽  
Phase Distribution ◽  
Maximum Energy ◽  
Treatment Temperature ◽  
Phase Identification

ABSTRACTThe phase transformation and the exchange coupling in (Ndo095Lao005)9.5FebaICOsNb 2BI05 have been investigated. Nanocomposites were obtained by treating amorphous precursors at temperatures ranging from 650TC to 9500C for 10 minutes. The magnetic properties were characterized via the vibrating sample magnetometer (VSM). X-ray diffraction (XRD), thermomagnetic analysis (TMA), and transmission electron microscopy (TEM) were used to perform phase identification, measure grain size, and analyze phase distribution. The strength of the exchange coupling between the magnetically hard and soft phases in the corresponding nanocomposite was analyzed via the AM-versus-H plot. It was found that the remanence (Br), coercivity (Hci), and maximum energy product (BHmax) obtained were affected by the magnetic phases present as well as the grain size of constituent phases and their distribution. The optimal magnetic performance, BHm, occurred between 700°C to 750°C, where the crystallization has completed without excessive grain growth. TMA and TEM indicated that the system was composed of three phases at this point, Nd2(Fe Co) 14B, ca-Fe, and Fe3B. The exchange coupling interaction among these phases was consistently described via the AM-versus-H plot up to 750°C. The Br, Hci, and BHmax degraded severely when the thermal treatment temperature increased from 750°C. This degradation may be attributed to the grain growth of the main phases, from 45 to 68nm, and the development of precipitates, which grew from 5nm at 750°C to 12nm at 850°C. Moreover, the amount of the precipitates was found to increase with the thermal treatment temperatures. The precipitates, presumably borides, may cause a decrease in the amount of the a-Fe and Fe 3B and result in a redistribution of the Co in the nanocomposites. The increase of the Co content in the Nd 2(Fe Co) 14B may explain the increase of its Curie temperature with the thermal treatment temperatures. In this paper, we examine the impacts of these factors on the magnetic properties of (Ndo 95Lao 05)9 5FebaICosNb2B10.5 nanocomposite.

Phase transformation, grain refinement and magnetic properties in melt-spun SmCo7−x(Cr3C2)x (x=0–0.25) ribbons

2009 ◽  
Vol 479 (1-2) ◽  
pp. 78-81 ◽  
Author(s):  
L.Y. Li ◽  
A. Yan ◽  
J.H. Yi ◽  
G.T. Zhang ◽  
W. Xie ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Phase Transformation ◽  
Grain Refinement ◽  
Melt Spun

Influence of Stacking Fault Energy on the Microstructures and Grain Refinement in the Cu-Al Alloys during Equal-Channel Angular Pressing

2010 ◽  
Vol 667-669 ◽  
pp. 379-384 ◽  
Author(s):  
X.H. An ◽  
Shi Ding Wu ◽  
Z.F. Zhang
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Al Alloys ◽  
Stacking Fault ◽  
High Recovery ◽  
Angular Pressing ◽  
High Recovery Rate ◽  
Refinement Mechanism ◽  
Stacking Fault Energies

The microstructural evolution and grain refinement of Cu-Al alloys with different stacking fault energies (SFEs) processed by equal-channel angular pressing (ECAP) were investigated. The grain refinement mechanism was gradually transformed from dislocation subdivision to twin fragmentation with tailoring the SFE of Cu-Al alloys. Concurrent with the transition of grain refinement mechanism, the grain size can be refined into from ultrafine region (1 m~100 nm) to the nanoscale (<100 nm) and then it is found that the minimum equilibrium grain size decreases in a roughly linear way with lowering the SFE. Moreover, in combination with the previous results, it is proposed that the formation of a uniform ultrafine microstructure can be formed more readily in the materials with high SFE due to their high recovery rate of dislocations and in the materials with low SFE due to the easy formation of a homogeneously-twinned microstructure.

Cavitation Behavior of Ultra-Fine Grained Ti-6Al-4V Alloy Produced by Equal-Channel Angular Pressing

2007 ◽  
Vol 551-552 ◽  
pp. 621-626
Author(s):  
Young Gun Ko ◽  
Yong Nam Kwon ◽  
Jung Hwan Lee ◽  
Dong Hyuk Shin ◽  
Chong Soo Lee
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Equal Channel Angular Pressing ◽  
Cavity Growth ◽  
Rate Sensitivity ◽  
Theoretical Models ◽  
Coarse Grained ◽  
Fine Grained ◽  
Angular Pressing ◽  
Cavitation Behavior

Cavitation behavior during superplastic flow of ultra-fine grained (UFG) Ti-6Al-4V alloy was established with the variation of grain size and misorientation. After imposing an effective strainup to 8 via equal-channel angular pressing (ECAP) at 873 K, alpha-phase grains were markedly refined from 11 μm to ≈ 0.3 μm, and misorientation angle was increased. Uniaxial-tension tests were conducted for initial coarse grained (CG) and two UFG alloys (ε = 4 and 8) at temperature of 973 K and strain rate of 10-4 s-1. Quantitative measurements of cavitation evidenced that both the average size and the area fraction of cavities significantly decreased with decreasing grain size and/or increasing misorientation. It was also found that, when compared to CG alloy, cavitation as well as diffused necking was less prevalent in UFG alloys, which was presumably due to the higher value of strain-rate sensitivity. Based on the several theoretical models describing the cavity growth behavior, the cavity growth mechanism in UFG alloys was suggested.

Improving magnetic properties of non-oriented electrical steels by controlling grain size prior to cold rolling

2019 ◽  
Vol 491 ◽  
pp. 165636 ◽  
Author(s):  
Ling-Zi An ◽  
Yin-ping Wang ◽  
Hong-Yu Song ◽  
Guo-Dong Wang ◽  
Hai-Tao Liu
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Cold Rolling ◽  
Electrical Steels

scholarly journals Designing (Ultra)Fine-Grained High-Entropy Alloys by Spark Plasma Sintering and Equal-Channel Angular Pressing

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1157
Author(s):  
Lisa-Marie Rymer ◽  
Thomas Lindner ◽  
Philipp Frint ◽  
Martin Löbel ◽  
Thomas Lampke
Keyword(s):  
Tensile Strength ◽  
Grain Refinement ◽  
Spark Plasma Sintering ◽  
Equal Channel Angular Pressing ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Fine Grained ◽  
Angular Pressing ◽  
Plasma Sintering ◽  
Spark Plasma

Single-phase, face-centered cubic (FCC) high-entropy alloys (HEA) are promising materials for future applications. In order to improve the mechanical properties, especially the tensile strength of these materials, this study focuses on the combination of spark plasma sintering (SPS) and equal-channel angular pressing (ECAP). The initial fine-grained microstructure produced by SPS is further refined by ECAP in a 90°-die. Optical microscopy and electron backscatter diffraction (EBSD) confirm this considerable grain refinement, leads to a grain size below 1 µm after 1 ECAP pass. An alternating arrangement of fine-grained areas and much coarser regions, aligned under an angle of approximately 27°, is found. Moreover, a first microstructural investigation of the twin structure is conducted. The mechanical behavior was investigated by hardness measurements and tensile testing. Both the hardness and tensile strength are remarkably increased after ECAP. In contrast, the uniform elongation and elongation at fracture are significantly reduced due to the strengthening mechanisms of strain hardening and grain refinement. It is concluded that the combination of SPS and ECAP is an attractive approach for designing (ultra)fine-grained HEAs with superior properties. The investigated techniques could be applied to understand the underlying microstructural mechanisms.

Grain Refinement and Texture Evolution in AZ31 Alloy during ECAP Process and Their Effects on Mechanical Properties

2005 ◽  
Vol 475-479 ◽  
pp. 549-554 ◽  
Author(s):  
H.S. Kim ◽  
Hyo Tae Jeong ◽  
Ha Guk Jeong ◽  
Woo Jin Kim
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Grain Refinement ◽  
Texture Evolution ◽  
Az31 Alloy ◽  
Mg Alloys ◽  
Fine Grained ◽  
Ecap Process ◽  
Texture Modification ◽  
Similar Texture

The softening of fine-grained ECAPed AZ31 Mg alloys could be ascribed to the texture modification during ECAP. Lower ECAP temperature is more effective in refining the microstructure. The strength of the ECAPed AZ 31 Mg alloys increased with decrease in grain size when they have similar texture.

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