Investigation of high strength metastable hypereutectic ternary Ti–Fe–Co and quaternary Ti–Fe–Co–(V, Sn) alloys
Investigation of high strength metastable hypereutectic ternary Ti–Fe–Co and quaternary Ti–Fe–Co–(V, Sn) alloys
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DOI：
10.1016/j.jallcom.2006.08.335
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发表时间：
2007-05
影响因子：
6.2
通讯作者：
D. V. Louzguine-Luzgin;L. V. Louzguina-Luzgina;H. Kato;A. Inoue
中科院分区：
文献类型：
--
作者：
D. V. Louzguine-Luzgin;L. V. Louzguina-Luzgina;H. Kato;A. Inoue
采用电弧熔炼法制备了直径25- 30 mm、高7- 10 mm的变形半球形高强度亚稳Ti-Fe-Co合金。用X射线衍射和扫描电镜研究了过共晶Ti-Fe-Co合金（Fe/Co比≥1）的组织结构，结果表明，合金由cP_2Ti（Fe，Co）化合物的一次枝晶和cP_2Ti（Fe，Co）化合物与无序BCC cI_2 β-Ti固溶体组成的共晶组成。最强的Ti-Fe-Co合金具有超共晶组织，并表现出超过2000 MPa的高强度和约15%的塑性变形。四元Ti 67 Fe 14 Co 14 Sn 5合金具有1830 MPa的高强度和24%的最大塑性应变。研究了Ti-Fe-Co和Ti-Fe-Co-Sn合金的变形行为和断口形貌。在相对软的共晶基体中形成具有金属间相的硬骨架的复合物状结构，使得能够实现高强度和延展性。合金的协调变形可以用初生Ti（Fe，Co）枝晶在较软共晶基体中的沿晶滑动来解释。粗初级枝晶和共晶棒的cP 2金属间相作为剪切应变和裂纹扩展的有效屏障，而细共晶棒的亚微米尺寸是相当毫不费力地切割变形带和裂纹。结果表明，钛基合金的高强度和高塑性值可以实现不使用注射模铸造或快速凝固程序。
The high strength metastable Ti–Fe–Co alloys were produced by arc-melting in the shape of distorted semi-spherical ingots with the dimensions of about 25–30mm in diameter and 7–10mm in height. The structure of the hypereutectic Ti–Fe–Co alloys (at Fe/Co ratio ≥1) studied by X-ray diffractometry and scanning electron microscopy consisted of the primary dendrites of an ordered cP2 Ti(Fe, Co) compound and an eutectic consisting of the cP2 Ti(Fe, Co) compound and a disordered BCC cI2 β-Ti solid solution. The strongest Ti–Fe–Co alloys have a hypereutectic structure and exhibit a high strength exceeding 2000MPa and a plastic deformation of about 15%. The quaternary Ti67Fe14Co14Sn5alloy exhibits a high strength of 1830MPa and the largest plastic strain of 24%. The deformation behavior and the fractography of Ti–Fe–Co and Ti–Fe–Co–Sn alloys are studied in detail. The formation of a composite-like structure with hard carcass of the intermetallic phase in the relatively soft eutectic matrix enabled both high strength and ductility. The accommodation deformation can be explained by the intergranular sliding of the primary Ti(Fe, Co) dendrites in the softer eutectic matrix. Rough primary dendrites and eutectic rods of the cP2 intermetallic phase act as efficient barriers for shear strain and cracks propagation, while fine eutectic rods of submicron size are quite effortlessly cut by deformation bands and cracks. It is shown that the high strength and ductility values for Ti-based alloys can be achieved without using the injection mould casting or rapid solidification procedure.