Nanomaterials by severe plastic deformation: review of historical developments and recent advances

International audienceSevere plastic deformation (SPD) is effective in producing bulk ultrafine-grained and nanostructured materials with large densities of lattice defects. This field, also known as NanoSPD, experienced a significant progress within the past two decades. Beside classic SPD methods such as high-pressure torsion, equal-channel angular pressing, accumulative roll-bonding, twist extrusion, and multi-directional forging, various continuous techniques were introduced to produce upscaled samples. Moreover, numerous alloys, glasses, semiconductors, ceramics, polymers, and their composites were processed. The SPD methods were used to synthesize new materials or to stabilize metastable phases with advanced mechanical and functional properties. High strength combined with high ductility, low/room-temperature superplasticity, creep resistance, hydrogen storage, photocatalytic hydrogen production, photocatalytic CO2 conversion, superconductivity, thermoelectric performance, radiation resistance, corrosion resistance, and biocompatibility are some highlighted properties of SPD-processed materials. This article reviews recent advances in the NanoSPD field and provides a brief history regarding its progress from the ancient times to modernity

Processing of eutectic Zn-5% Al alloy by equal-channel angular pressing

Multi-pass equal-channel angular pressing (ECAP) was applied to the eutectic Zn-5% Al alloy as a first step in the examination of the binary Zn-Al alloy system by using two different processing routes: route A, where the sample is pressed repetitively through the die without rotation, and route C, where the sample is rotated by 180° after each pass. A three-block die for ECAP was designed and manufactured. Evolution of hardness was investigated and microstructural changes were noted during ECAP. Variations in the applied load during ECAP of the alloy were analyzed, and the relationship between maximum load and hardness was discussed. It was observed that the equiaxed grain structure of the as-received alloy completely disappeared and instead a banded structure was formed during the ECAP process. Hardness of the alloy decreased with increasing number of passes for both processing routes. The applied load during ECAP increased up to a maximum value, and this was followed by a decrease until the end of pressing in all processing conditions. The maximum load required for the ECAP of the alloy decreased for both routes with increasing number of passes. It was observed that the hardness and the maximum load showed similar trends with number of passes for both processing routes. © 2004 Elsevier B.V. All rights reserved

Microstructure, mechanical properties and formability of friction stir welded dissimilar materials of IF-steel and 6061 Al alloy

Kucukomeroglu, Tevfik/0000-0002-4392-9966; Aktarer, Semih Mahmut/0000-0001-5650-7431WOS: 000471270400007AA 6061 alloy and interstitial-free (IF) steel plates were joined by the friction stir welding (FSW) method, and the microstructure, mechanical properties, and biaxial stretch formability of the friction stir welded (FSWed) parts were investigated. the results indicate that the FSWed parts showed optimum tensile strength during FSW with the 0.4-mm offset position of the tool. the Fe4Al13 intermetallic compound formed in the defect-free intersection of AA 6061 and IF-steel plates during FSW. the hardness of the IF-steel part of the FSWed region increased almost 90% relative to its initial hardness of HV0.2 105. the tensile and yield strengths of FSWed regions were approximately 170 MPa and 145 MPa, respectively. According to the formability tests, the Erichsen Index (EI) of the IF-steel, AA 6061, and the FSWed samples were determined to be 2.9 mm, 1.9 mm, and 2.1 mm, respectively. the EI of the FSWed sample was almost the same as that of the AA 6061 alloy. However, it decreased compared with that of the IF-steel. the force at EI (F-EI) was approximately 1180 N for the FSWed condition. This value is approximately 70% higher than that of AA 6061 alloy.World Academy of Sciences (TWAS) under the Visiting Researchers program of TWAS-UNESCO Associateship Scheme [3240290077]Dr. G. Purcek was supported by "The World Academy of Sciences (TWAS) under the Visiting Researchers program of TWAS-UNESCO Associateship Scheme (No. 3240290077).

The mechanical compression performance of ultra-fine grained stainless steel pyramidal lattice core

Demirtas, Muhammet/0000-0002-7357-3892WOS: 000473062100001Severe plastic deformation (SPD) techniques are prospective ones having ability for desirable high mechanical properties to be achieved without any chemical change in metals. Equal-channel angular pressing (ECAP), one of SPD techniques, was used to obtain ultra-high mechanical compressive response of stainless steel pyramidal lattice core. For this purpose, the stainless steel 304 L samples were processed by ECAP at 500 degrees C. Then, it was sliced into struts and built lattice core after bending processes. At the compression tests, the ECAP lattice core has huge mechanical properties, at nearly two times collapse load and energy absorption values

Microstructural and Mechanical Evolution of a Low Carbon Steel by Friction Stir Processing

Aktarer, Semih Mahmut/0000-0001-5650-7431WOS: 000404516100023A low carbon steel (Grade A) was subjected to friction stir processing (FSP), and the effect of FSP on the microstructure and mechanical properties was investigated systematically. It was found that two distinct zones called stir zone (SZ) and heat-effected zone (HAZ) were formed during FSP. The SZ and HAZ consist mainly of ferrite, widmanstatten ferrite, ferrite+cementite aggregates, and martensite. FSP considerably refined the microstructure of the steel by means of dynamic recrystallization mechanism and formed a volumetric defect-free basin-like processed region. The ferritic grain size of the steel decreased from 25 A mu m in the coarse-grained state to about 3 A mu m in the fine-grained state, and the grains formed were separated mostly by high angle of misorientation with low density of dislocations. This microstructural evolution brought about a considerable increase in both hardness and strength values without a considerable decrease in ductility. Ultrafine-grained microstructure formed around and just beneath the pin increased the hardness of the steel from 140 Hv0.3 to about 245 Hv0.3. However, no hardness uniformity was formed throughout the processed zone due to the changes in deformation- and temperature-induced microstructure. Both yield and tensile strength values of processed zone increased from 256 and 435 MPa to about 334 and 525 MPa, respectively.World Academy of Sciences (TWAS) under the Visiting Researchers Program of TWAS-UNESCO Associateship Scheme [3240260896]Dr. G. Purcek was supported by The World Academy of Sciences (TWAS) under the Visiting Researchers Program of TWAS-UNESCO Associateship Scheme (Ref. 3240260896). The authors would like to thank Dr. T. Kucukomeroglu for his help in conducting the FSP

Nanomaterials by severe plastic deformation: review of historical developments and recent advances

International audienceSevere plastic deformation (SPD) is effective in producing bulk ultrafine-grained and nanostructured materials with large densities of lattice defects. This field, also known as NanoSPD, experienced a significant progress within the past two decades. Beside classic SPD methods such as high-pressure torsion, equal-channel angular pressing, accumulative roll-bonding, twist extrusion, and multi-directional forging, various continuous techniques were introduced to produce upscaled samples. Moreover, numerous alloys, glasses, semiconductors, ceramics, polymers, and their composites were processed. The SPD methods were used to synthesize new materials or to stabilize metastable phases with advanced mechanical and functional properties. High strength combined with high ductility, low/room-temperature superplasticity, creep resistance, hydrogen storage, photocatalytic hydrogen production, photocatalytic CO2 conversion, superconductivity, thermoelectric performance, radiation resistance, corrosion resistance, and biocompatibility are some highlighted properties of SPD-processed materials. This article reviews recent advances in the NanoSPD field and provides a brief history regarding its progress from the ancient times to modernity