Cobalt-doped Ti-48Al-2Cr-2Nb alloy fabricated by cold compaction and pressureless sintering

被引：34
作者：
Xia, Y. [1 ]
Yu, R. [2 ]
Schaffer, G. B. [1 ]
Qian, M. [1 ]
机构：
[1] Univ Queensland, Sch Mech & Min Engn, ARC Ctr Excellence Design Light Met, Brisbane, Qld 4072, Australia
[2] South Univ Sci & Technol China, Dept Micronano Mat & Device, Shenzhen 518055, Peoples R China
来源：
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING | 2013年 / 574卷
基金：
澳大利亚研究理事会;
关键词：
Titanium aluminide; Sintering; Cobalt; Mechanical properties; GAMMA-TITANIUM ALUMINIDES; MECHANICAL-PROPERTIES; SELF-DIFFUSION; OXIDATION BEHAVIOR; WC-CO; MICROSTRUCTURE; POWDER; INTERDIFFUSION; COPPER; OXYGEN;
D O I：
10.1016/j.msea.2013.03.023
中图分类号：
TB3 [工程材料学];
学科分类号：
0805 ; 080502 ;
摘要：
An addition of 1.5 at% Co to Ti-48Al-2Cr-2Nb (in at%) transformed the alloy from essentially unsinterable to fully sinterable at 1300 degrees C. This, together with a simple powder coating process developed recently, has allowed near-net shape fabrication of the alloy for the first time by cold compaction and pressureless sintering. The addition of Co results in the formation of an intermediate face centred cubic (fcc) CoAl2Ti phase prior to 1220 degrees C during heating. It subsequently reacts with an alpha phase leading to the formation of a Co-containing, wettable sintering liquid through a two-step process, CoAl2Ti+alpha -> Liquid at 1256.2 degrees C and CoAl2Ti+alpha ->gamma-TiAl+Liquid at 1267.2 degrees C, and therefore full densification of the alloy. Without Co, sintering of the Ti-48Al-2Cr-2Nb alloy powder at 1300 degrees C is controlled by the slow self-diffusion of Ti and interdiffusion of Ti and Al according to the activation energy determined. Transmission electron microscopy (TEM) identified an fcc CoAl2Ti phase and a hexagonal close packed (hcp) Co-enriched Ti(Al, Co, Cr, Nb) phase in the final as-sintered Ti-48Al-2Cr-2Nb-1.5Co alloy. They both form during cooling at 1240 degrees C through Liquid+alpha -> CoAl2Ti+Ti (Al, Co, Cr, Nb). The tensile and compressive properties of the as-sintered Ti-48Al-2Cr-2Nb-1.5Co alloy were compared to the original General Electric (GE) Ti-48Al-2Cr-2Nb alloy fabricated by casting or metal injection moulding. (C) 2013 Elsevier B.V. All rights reserved.
引用
收藏
页码：176 / 185
页数：10
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