Consolidation of Nanostructured Metal Powders Produced by Modulation-Assisted Machining

2018 ◽  
Author(s):  
James B. Mann ◽  
Christopher Saldana ◽  
Srinivasan Chandrasekar
Keyword(s):  
Extrusion Direction ◽  
Critical Time ◽  
Metal Powders ◽  
Fine Grained ◽  
Extrusion Die ◽  
Transmission Electron ◽  
Ultrafine Grained ◽  
Nanocrystalline Aluminum ◽  
Ultrafine Grained Microstructure ◽  
Nanostructured Metal

In the present study, nanocrystalline aluminum alloy (Al3003-H14) particulate produced by modulation-assisted machining (MAM) is consolidated by indirect extrusion. The extrusion die was simultaneously heated below the critical time-temperature conditions for recrystallization. Experimental consolidation of platelet shaped particles showed a distinct elongation of grain size in the primary extrusion direction. Metallographic and transmission electron microscopy observations revealed ultrafine grained microstructure with grains having similar orientations across grain boundaries. The shear from indirect extrusion combined with the uniform distribution of alloy particulates by MAM provides a potential route for bulk consolidation of metals and alloys with ultra-fine grained microstructure.

scholarly journals Improvement of Pitting-Corrosion Resistance of Ultrafine-Grained 7475 Al Alloy by Aging

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 360
Author(s):  
Ewa Ura-Bińczyk
Keyword(s):  
Corrosion Resistance ◽  
Pitting Corrosion ◽  
Al Alloy ◽  
Subsequent Aging ◽  
Fine Grained ◽  
Transmission Electron ◽  
Pitting Corrosion Resistance ◽  
Ultrafine Grained ◽  
Ultrafine Grained Microstructure

The effect of aging on the resistance to pitting corrosion of ultrafine-grained 7475 aluminium (Al) alloy processed by hydrostatic extrusion (HE) is studied. Differences in the microstructure were investigated using secondary electron (SEM) and transmission electron microscopy (TEM). Corrosion tests were performed in 0.1 M NaCl, and characterization of corroded surface was performed. The results of this work show that the pitting susceptibility of ultra-fine grained 7475Al is related to the distribution of MgZn2 precipitates. After HE, the formation of An ultrafine-grained microstructure at the grain boundaries of ultrafine grains is observed, while subsequent aging results in the formation of MgZn2 precipitates in the grain interior. Grain refinement increases susceptibility to localized attack, while the subsequent aging improves the overall corrosion resistance and limits the propagation of corrosion attack.

Grain Refinement of Copper Alloys by Equal Channel Angular Pressing

2004 ◽  
Vol 449-452 ◽  
pp. 177-180 ◽  
Author(s):  
Cha Yong Lim ◽  
Jae Hyuck Jung ◽  
Seung Zeon Han
Keyword(s):  
Grain Size ◽  
Equal Channel Angular Pressing ◽  
Copper Alloys ◽  
Metallic Materials ◽  
Fine Grained ◽  
Angular Pressing ◽  
Fine Grain ◽  
Transmission Electron ◽  
Ultrafine Grained ◽  
Average Grain Size

The equal channel angular pressing (ECAP) is one of the methods to refine the grain size of metallic materials. This study investigates the effect of ECAP process on the formation of the fine grain size in oxygen free Cu and Cu alloys. The average grain size has been refined from 150 µm before ECAP to 300 nm. Microstructure was analyzed by transmission electron micrography (TEM). The diffraction pattern of the selected area confirmed the formation of ultrafine-grained structure with high angle grain boundaries after 8 cycles of ECAP. Mechanical properties such as microhardness and tensile properties of the ultra-fine grained copper materials have been investigated.

Ultrafine Grained Microstructure in Al-Cu-Si Alloy Obtained by Accumulative Roll Bonding Process

2011 ◽  
Vol 702-703 ◽  
pp. 157-160
Author(s):  
Wahdat Ullah ◽  
Gouthama
Keyword(s):  
Accumulative Roll Bonding ◽  
Dynamic Recovery ◽  
Bonding Process ◽  
Ultrafine Grain ◽  
Strain Condition ◽  
Accumulative Roll Bonding Process ◽  
Roll Bonding ◽  
Transmission Electron ◽  
Ultrafine Grained ◽  
Ultrafine Grained Microstructure

An Ultrafine grain (UFG) microstructure is developed on the sheet of Al-2.4wt%Cu-0.3wt%Si alloy after three passes of accumulative roll bonding (ARB) process. The detailed of the microstructural features and phases at different strain condition has been studied by transmission electron microscopy (TEM). Observation indicates at the possibility of dynamic recovery and recrystallisation during the ARB processing itself. The material becomes ultrafine grains after three passes of ARB itself with the formation of dynamically recrystallised grains all over the sample. TEM evidence is presented in support of this proposal.

New Type of Ultra-Fine Grained Microstructure in Ti-6Al-4V Alloy for Enhancing Superplasticity

2012 ◽  
Vol 735 ◽  
pp. 322-326
Author(s):  
Hiroaki Matsumoto ◽  
Sang Hak Lee ◽  
Yoshiki Ono ◽  
Akihiko Chiba
Keyword(s):  
Heterogeneous Nucleation ◽  
High Angle Boundary ◽  
Hot Compression ◽  
High Angle ◽  
Fine Grained ◽  
Ultrafine Grained ◽  
New Type ◽  
High Fraction ◽  
Ultrafine Grained Microstructure

This work presents a formation of ultrafine-grained microstructure (d ~ 0.2 μm) with high fraction of high-angle boundary in industrial Ti–6Al–4V alloy produced by the hot compression of a sample with the acicular α′martensite starting microstructure . It is found that heterogeneous nucleation becomes dominant in the case of the α’ starting microstructure.α

Formation of Ferrite-Cementite Ultrafine Grained Microstructure by Warm Compression for SM490 Martensite Steel

2007 ◽  
Vol 558-559 ◽  
pp. 539-544
Author(s):  
J.H. Li ◽  
Ping Guang Xu ◽  
Yo Tomota ◽  
Yoshitaka Adachi
Keyword(s):  
Dynamic Recrystallization ◽  
Low Carbon Steel ◽  
Block Size ◽  
Low Carbon ◽  
Fine Grained ◽  
Orientation Imaging ◽  
Ultrafine Grained ◽  
Different Temperatures ◽  
Dynamic Recrystallization Behavior ◽  
Ultrafine Grained Microstructure

The low carbon steel, SM490 was austenized at different temperatures followed by quenching into water to obtain martensite microstructures with different grain sizes. Then specimens were heated up to 600°C followed by warm-compression at έ=1.7x10-3 s-1 (strain rate) to investigate the dynamic recrystallization behavior. The influence of pre-tempering before compression was also investigated. The microstructure observations were performed with FE-SEM and orientation imaging analysis with EBSD. It is confirmed that the dynamic recrystallization occurred in the tempered martensite as well as the as-quenched marteniste, resulting in fine grained ferrite microstructure with about 2μm. The dynamic recrystallization grain size is hardly dependent on the block size of initial martensite.

Effects of Ball Milling Processing on Solidified TiC-TiB2 Composites Prepared by Combustion Synthesis in High Gravity Field

2014 ◽  
Vol 602-603 ◽  
pp. 467-472
Author(s):  
Zhong Min Zhao ◽  
De Jun Yin ◽  
Long Zhang ◽  
Shuan Jie Wang ◽  
Min Quan Wang
Keyword(s):  
Gravity Field ◽  
Ball Milling ◽  
Combustion Synthesis ◽  
Ignition Temperature ◽  
Liquid Product ◽  
High Gravity ◽  
Fine Grained ◽  
Ultrafine Grained ◽  
High Gravity Field ◽  
Ultrafine Grained Microstructure

By combining ball milling processing with combustion synthesis in ultrahigh gravity field, the solidified TiC-TiB2 composite was achieved with fine-grained and ultrafine-grained microstructure. It is considered that taking balling milling processing to mechanically activate powder blend promotes thermal explosion to occur in ultrahigh gravity field by reducing ignition temperature, increases sharply the actual temperature of full-liquid product, thereby not only accelerating liquid-liquid separation of TiC-TiB2 liquid and Al2O3 droplets, but also refining the solidified microstructure by enhancing undercooling of TiC-TiB2 liquid, finally, brings about a series of dramatic improvements in densification and mechanical properties of the ceramic.

Microstructures and Properties of Solidified TiC-TiB2 Ceramic Composites with Increasing Cr Metallic Binder Prepared by Combustion Synthesis in High-Gravity Field

2012 ◽  
Vol 512-515 ◽  
pp. 344-349 ◽  
Author(s):  
Liang Xiang Liu ◽  
Long Zhang ◽  
Zhong Min Zhao ◽  
Min Quan Wang
Keyword(s):  
Gravity Field ◽  
Combustion Synthesis ◽  
Ceramic Composites ◽  
High Gravity ◽  
Ti Alloy ◽  
Fine Grained ◽  
Ultrafine Grained ◽  
High Gravity Field ◽  
Shrinkage Cavities ◽  
Ultrafine Grained Microstructure

By increasing addition amount of (CrO3 + Al) subsystem in (B4C + Ti) system, the solidified TiC-TiB2 composites with a series of mass fraction of Cr binder were achieved by combustion synthesis in high-gravity field. The microstructures of the solidified ceramics presented a number of fine TiB2 platelets embedded in TiC grains, Cr-Ti alloy or between TiC grains and Cr-Ti alloy. The increased Cr binder in the ceramic not only brought about the enhanced densification of the ceramic due to fill-up of Cr-Ti liquid in shrinkage cavities between solidified TiC and TiB2 phases, but more importantly made fine-grained even ultrafine-grained microstructure achieved because of the accelerated nucleation and the decelerated growth of TiB2 at initial stage of material solidification. As a result of the achievement of fine-grained even ultrafine-grained microstructure along with the enhanced toughneing mechanisms contributed by the refined TiB2 platelets and the increased plastic phases of Cr-Ti alloy, the solifidied TiC-TiB2 composite containing 20.7 % Cr binder presented the maximun values of 1045 ± 25 MPa and 21.5 ± 1.6 MPa • m 0.5, simultaneously, in flexural strength and fracture toughness along with the moderate hardness of 17.5 ± 2.2 GPa.

Microstructural Studies of Al 5083 Alloy Deformed through Cryorolling

2012 ◽  
Vol 585 ◽  
pp. 376-380 ◽  
Author(s):  
Dharmendra Singh ◽  
Palukuri Nageswararao ◽  
R. Jayaganthan
Keyword(s):  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Second Phase ◽  
Transmission Electron ◽  
Ultrafine Grained ◽  
Second Phase Particles ◽  
Al 5083 Alloy ◽  
Short Annealing ◽  
Average Size ◽  
Ultrafine Grained Microstructure

In the present work to investigate the effect of rolling at very low temperature on microstructure of Al 5083 alloy, it was subjected to rolling at room temperature and immediate quenching at liquid nitrogen temperature up to different strain levels. The microstructure of deformed material has been studied using Electron back scattered diffraction (EBSD) and Transmission electron microscopy (TEM) techniques. A homogeneous ultrafine grained microstructure of an average size of 300 nm with well defined grain boundaries could be achieved with an effective rolling strain of only 2.3 followed by short annealing at 300 °C for 6 min. The effect of second phase particles on grain refinement at different stains is discussed. It was observed that increased dislocation density due to effective suppression of dynamic recovery by immediate quenching in liquid nitrogen temperature after each successive rolling passes leads to increased stored energy which further leads to formation of homogeneous ultrafine grained microstructure after short annealing subsequently.

Development of Fine-Grained High-Mn Steelby Cold Rolling and Annealing

2016 ◽  
Vol 838-839 ◽  
pp. 434-439 ◽  
Author(s):  
Zhanna Yanushkevich ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev ◽  
Christian Haase ◽  
Dmitri A. Molodov
Keyword(s):  
Cold Rolling ◽  
Shear Banding ◽  
Mechanical Twinning ◽  
Rolling Reduction ◽  
Fine Grained ◽  
Noticeable Increase ◽  
Ultrafine Grained ◽  
Cold Rolling And Annealing ◽  
Ultrafine Grained Microstructure ◽  
Ultrafine Grained Steel

The regularities of static recrystallization in an Fe-0.3C-17Mn-1.5Al TWIP steel subjected to cold rolling and annealing were studied. The cold rolling led to noticeable increase in the dislocation density, extensive mechanical twinning and shear banding. The subsequent annealing resulted in the development of recovered or recrystallized microstructure depending on the rolling reduction and the annealing temperature. An increase in the rolling reduction promoted the recrystallization development, which led to ultrafine-grained microstructure with a grain size below 10 μm. The developed ultrafine-grained steel samples are characterized by beneficial mechanical properties.

Melt Modification and Microstructure Homogeneity of Solidified TiC-TiB2 Composites Prepared by Combustion Synthesis in Ultrahigh Gravity Field

2013 ◽  
Vol 833 ◽  
pp. 125-129
Author(s):  
Hao Zhang ◽  
Zhong Min Zhao ◽  
Long Zhang ◽  
Shuan Jie Wang
Keyword(s):  
Gravity Field ◽  
Combustion Synthesis ◽  
Stokes Flow ◽  
High Energy ◽  
Adiabatic Temperature ◽  
Full Density ◽  
Reactive System ◽  
Refined Microstructure ◽  
Ultrafine Grained ◽  
Ultrafine Grained Microstructure

By introducing (CrO3+Al) high-energy thermit into (Ti+B4C) system and designing adiabatic temperature of reactive system as 3000°C,3200°C, 3400°C, 3600°C and 3800°C respectively, a series of solidified TiC-TiB2were prepared by combustion synthesis in ultrahigh gravity field with the acceleration 2000 g. XRD, FESEM and EDS results showed that the solidified TiCTiB2were composed of a number of TiB2primary platelets, irregular TiC secondary grains, and a few of isolated Al2O3inclusions and Cr-based alloy. Because of the enhanced Stokes flow in mixed melt with the increased adiabatic temperature, Al2O3droplets were promoted to float up and separate from TiC-TiB2-Me liquid while constitutional distribution became more and more uniform in TiC-TiB2-Me liquid, resulting in not only the sharply-reduced Al2O3inclusions in the solidified ceramic but also the refined microstructure and the improved homogeneity in the ceramic, and ultrafine-grained microstructure with a average thickness of TiB2platelets smaller than 1μm began to appear in near-full-density ceramic as the adiabatic temperature exceeded 3600°C, so the densification, fracture toughness and flexural strength of the ceramic were enhanced with the increased adiabatic temperature of the reactive system.

Sign in / Sign up

Export Citation Format

Share Document