摘要
提出了一种基于共晶转变形成液相的半固态烧结新技术,通过调控共晶转变的相组成(或共晶液相的含量),利用半固态烧结共晶复相系非晶粉末成功制备出高强韧新型双尺度结构Ti_(52.1)Fe_(21.7)Co_(8.2)Nb_(12.2)Al_(5.8)合金。其双尺度结构为超细晶bcc β-Ti和超细晶bcc Ti(Fe,Co)构成的层片共晶基体包围细晶等轴状fcc Ti_2(Co,Fe)第二相,与目前文献报道的双尺度结构明显不同。该双尺度结构合金具有超高的屈服强度(2050 MPa)和较大的塑性应变(19.7%),综合性能优于目前文献报道的双尺度结构钛合金。
According to HalI-Petch relationship, high strength of nano-grain and ultrafine-grain metallic materials are always accompanied by the cost of ductility because of the lack of work hardening induced by rare or absent dislocation or slip band. And various strategies including semi-solid processing accompanied by rapid solidification, recrystallization induced by plastic deformation and heat treatment, consolidation of blended powders with different grain sizes, and so on, have been developed to fabricate so-called bimodal/multimodal microstructures in the pursuit of high strength and no sacrificing ductility. As one of the most significant types of phase transformation in metallography, eutectic reaction was frequent- ly utilized to tailor phase constitution and its microstructure due to high strength resulted from resultant la- mellar eutectic structure. Generally, eutectic structure is more common in solidification and even tradition- al semi-solid processing for low melting point alloys （such as aluminum and magnesium alloys）. In this work, a fundamentally novel approach of semi-solid sintering stemmed from the formation of liquid phase induced by eutectic transformation is introduced. Through regulation of the phase composition of eutectic transformation （or eutectic liquid content）, novel bimodal Ti52.1Fe21.7Co8.2Nb12.2Al5.8 alloy with high-strength and large-ductility was successfully fabricated by semi-solid sintering of amorphous alloy powder with multi-phase eutectic system. The fabricated bimodal microstructure consists of fine nearly equiaxed fcc Ti2（Co, Fe） embedded into ultrafine lamellar eutectic matrix containing bcc β-Ti and bcc Ti（Fe, Co） lamellae, which is different from bimodal microstructures reported so far. The fabricated bimodal alloy exhibits ultra-high yield strength of 2050 MPa and large plastic strain of 19.7%, superior to those of bimodal titanium alloys reported so far. The method is conducive to process high-performance new structural metallic alloys in high melting p
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2017年第4期440-446,共7页
Acta Metallurgica Sinica
基金
国家自然科学基金项目Nos.51574128和51627805
广东省自然科学基金研究团队项目No.2015A030312003~~
关键词
钛合金
双尺度结构
半固态烧结
放电等离子烧结
共晶转变
titanium alloy, bimodal microstructure, semi-solid sintering, spark plasma sintering,eutectic transformation
