Ag/Ti3AlC2 Composites Prepared by Equal Channel Angular Pressing Followed by Heat Treatment
(2.School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan, China 243002)
(3.College of Mechanics and Materials, Hohai University, Nanjing, China 210098)
【Abstract】Equal channel angular pressing (ECAP) followed by heat treatment was carried out to prepare Ag/Ti3AlC2 composites. The effects of heat treatment on the resistivities and mechanical properties of the Ag/Ti3AlC2 composites were investigated. Results show that ECAP effectively densifies the Ag/Ti3AlC2 compacts, and the layered Ti3AlC2 particles are delaminated and aligned due to the shearing effect during ECAP. Alignment of Ti3AlC2 particles resulted in the anisotropy of electrical and mechanical properties of the composites. Perpendicular to the alignment of Ti3AlC2 particles displayed high resistivity and compressive strength. Moreover, the resistivity and compressive strength increased with following heat treatment, yielding the maximum at 800 ℃. These increments were attributed to the enhanced interfacial reactions between Ag and Ti3AlC2 at high temperatures. The findings in this study indicate that densification and microstructural control of Ag/MAX composites can be achieved simultaneously by ECAP, while the following heat treatment can tailor their properties.
【Keywords】 equal channel angular pressing (ECAP); Ag/Ti3AlC2; alignment; heat treatment;
(Translated by LI ZP)
 DING J X, SUN Z M, ZHANG P G, et al. Current research status and outlook of Ag-based contact materials. Materials Reports, 2018, 32 (1): 58–66.
 SUN Z M. Progress in research and development on MAX phases: a family of layered ternary compounds. International Materials Reviews, 2011, 56 (3): 143–166.
 DING J X, TIAN W B, ZHANG P G, et al. Arc erosion behavior of Ag/Ti3AlC2 electrical contact materials. Journal of Alloys and Compounds, 2018, 740: 669–676.
 LIU M M, CHEN J L, CUI H, et al. Ag/Ti3AlC2 composites with high hardness, high strength and high conductivity. Materials Letters, 2018, 213: 269–273.
 DING J X, TIAN W B, WANG D D, et al. Corrosion and degradation mechanism of Ag/Ti3AlC2 composites under dynamic electric arc discharging. Corrosion Science, 2019, 156: 147–160.
 WANG D D, TIAN W B, MA A B, et al. Anisotropic properties of Ag/Ti3AlC2 electrical contact materials prepared by equal channel angular pressing. Journal of Alloys and Compounds, 2019, 784: 431–438.
 ZHANG M, TIAN W B, ZHANG P G, et al. Microstructure and properties of Ag-Ti3SiC2 contact materials prepared by pressureless sintering. International Journal of Minerals, Metallurgy, and Materials, 2018, 25 (7): 810–816.
 DING J X, TIAN W B, ZHANG P G, et al. Preparation and arc erosion properties of Ag/Ti2SnC composites under electric arc discharging. Journal of Advanced Ceramics, 2019, 8 (1): 90–101.
 DING J X, TIAN W B, WANG D D, et al. Microstructure evolution, oxidation behavior and corrosion mechanism of Ag/Ti2SnC composite during dynamic electric arc discharging. Journal of Alloys and Compounds, 2019, 785: 1086–1096.
 DING J X, TIAN W B, WANG D D, et al. Arc erosion and degradation mechanism of Ag/Ti2AlC composite. Acta Metallurgica Sinica, 2019, 55 (5): 627–637.
 AFONIN M P, BOIKO A V. Effect of structural anisotropy on contact properties in a silver-graphite composite. Powder Metallurgy and Metal Ceramics, 2005, 44 (1): 84–87.
 XU C, YI D, WU C, et al. Microstructures and properties of silver-based contact material fabricated by hot extrusion of internal oxidized Ag-Sn-Sb alloy powders. Materials Science and Engineering: A, 2012, 538: 202–209.
 CHEN YL, YANG CF, YEH JW, et al. A novel process for fabricating electrical contact SnO2/Ag composites by reciprocating extrusion. Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science, 2005, 36A (9): 2441–2447.
 BALOG M, SIMANCIK F, BAJANA O, et al. ECAP vs. direct extrusion-techniques for consolidation of ultra-fine Al particles. Materials Science and Engineering: A, 2009, 504 (1): 1–7.
 SEGAL V M. Materials processing by simple shear. Materials Science and Engineering: A, 1995, 197 (2): 157–164.
 MA A, NISHIDA Y, SUZUKI K, et al. Characteristics of plastic deformation by rotary-die equal-channel angular pressing. Scripta Materialia, 2005, 52 (6): 433–437.
 HAGHIGHI R D, JAHROMI S A J, MORESEDGH A, et al. A comparison between ECAP and conventional extrusion for consolidation of aluminum metal matrix composite. Journal of Materials Engineering and Performance, 2012, 21 (9): 1885–1892.
 DERAKHSHANDEH H R, JAHROMI A J. An investigation on the capability of equal channel angular pressing for consolidation of aluminum and aluminum composite powder. Materials & Design, 2011, 32 (6): 3377–3388.
 LAPOVOK R. Damage evolution under severe plastic deformation. International Journal of Fracture, 2002, 115 (2): 159–172.
 NAGASEKHAR A V, TICK-HON Y, RAMAKANTH K S. Mechanics of single pass equal channel angular extrusion of powder in tubes. Applied Physics A-Materials Science & Processing, 2006, 85 (2): 185–194.
 LIU M, CHEN J, CUI H, et al. Temperature-driven deintercalation and structure evolution of Ag/Ti3AlC2 composites. Ceramics International, 2018, 44 (15): 18129–18134.
 SU L Y, WANG P F, XU Z B, et al. Oscillatory shear-induced alignment of ketjen black conductive particles in polylactic acid and its effect on the electrical anisotropy. Journal of Polymer Science Part B-Polymer Physics, 2016, 54 (3): 369–373.
 XU W X, JIA M K, GONG Z. Thermal conductivity and tortuosity of porous composites considering percolation of porous network: from spherical to polyhedral pores. Composites Science and Technology, 2018, 167: 134–140.
 BARSOUM M W. The Mn+1AXn phases: a new class of solids; thermodynamically stable nanolaminates. Progress in Solid State Chemistry, 2000, 28 (1–4): 201–281.