(1.中南大学 粉末冶金国家重点实验室,长沙 410083;
2.长沙交通学院 汽车和机电工程系,长沙 410076;
3.北京科技大学 材料科学与工程学院, 北京 100083)
摘 要: 通过非自耗磁控电弧炉熔铸和700℃,20h高温退火处理, 制备出了含铬量为18%~30%(质量分数)的含TiCr2 Laves相过共析钛铬合金,并研究了合金的组织变化规律。结果表明,稳定化系数为2.57~4.62的过共析钛铬合金经过熔炼后,在随炉冷却条件下得到的是单相β-Ti组织;铸态合金在700℃保温退火时,金属间化合物TiCr2不仅沿晶界生成并形成连续分布,还在基体内部弥散析出;在随后的空冷过程中合金内局部发生β-Ti→α-Ti+TiCr2共析分解。合金含铬量越高,在高温退火时析出的TiCr2量越多,尺寸越粗大,合金的硬度也越高。电弧熔炼+700℃,20h高温退火是一种制备含Laves相过共析钛铬合金的可行工艺。
关键字: 钛铬合金;共析转变;TiCr2;α-Ti;β-Ti
Ti-Cr alloys with Laves phase TiCr2
(1.State Key Laboratory for Powder Metallurgy,
Central South University,Changsha 410083, China;
2.Automotive and Electromechanical Engineering Department,
Changsha Communications University,Changsha 410076, China;
3.School of Materials Science and Engineering,
University of Science and Techno logy Beijing,
Beijing 100083, China)
Abstract:Hypereutectoid Ti-Cr alloys (18%~30%Cr, mass fraction) with Laves phase Ti Cr2 were prepared by means of non-consumable electrode arc melting and annealing at 700℃ for 2h. The as-cast and as-annealing microstructures were investigated respectively. The results reveal that the microstructure of melted alloy followed by furnace cooling with a stabilization coefficient of 2.77~4.62 are solely composed of β-Ti. Laves phase TiCr2 will be precipitated along the grain boundaries and in the matrix when the alloys are annealed at 700℃, and an eutectoid transformation β-Ti→α-Ti+TiCr2 happens in some parts of the alloy during air cooling. The higher the chromium content,the more the quantity and the larger the size of TiCr2 and there for e the higher the hardness of the alloy is. Arc melting+700℃, 20h annealing is a feasible process for the preparation of hypereutectoid Ti-Cr alloys with Laves phase TiCr2.
Key words: Ti-Cr alloys;eutectoid transformation;TiCr2; α-Ti;β-Ti