Evolution of the microstructure and hardness of the Ti-Si alloys during high temperature heat-treatment
Evolution of the microstructure and hardness of the Ti-Si alloys during high temperature heat-treatment
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Ti-Si合金高温热处理过程中显微组织和硬度的演变
DOI：
10.1016/j.jallcom.2009.01.017
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发表时间：
2009-06-24
影响因子：
6.2
通讯作者：
Du, Yong
中科院分区：
文献类型：
--
作者：
Zhan, Yongzhong;Zhang, Xinjiang;Du, Yong
Ti-8 Si、Ti-13.67Si和Ti-23 S的样品（at.%）采用真空熔炼技术制备了合金，并在真空环境中于1373 K和1473 K下热处理2 h。采用光学显微镜（OM）、X射线衍射仪（XRD）、扫描电镜（SEM）、能谱仪（EDX）和硬度计对铸态和退火态试样进行了分析。在高温热处理过程中，铸态Ti-8 Si合金中的Ti 5Si 3 + Ti相最终转变为弥散分布在Ti基体中的近等轴Ti 5Si 3晶粒。对于Ti-13.67Si合金，与铸态合金中的片层晶粒相比，Ti 5Si 3晶粒最终也转变为近等轴晶粒。与铸态合金相比，退火处理后Ti-85 i和Ti-13.67Si合金的维氏硬度均有所提高。而Ti-23 Si合金的显微组织没有明显变化。因此，高温热处理后，维氏硬度反而下降。Ti-Si合金的显微组织演变与高温热处理过程中Si原子在Ti/Ti 5Si 3界面的扩散有关，热处理使Ti 5Si 3颗粒尽可能均匀地分布在连续的α-Ti基体中。由于Ti-23 Si合金在热处理过程中初生Ti 5Si 3相颗粒的稳定性，该任务无法实现。(C)2009爱思唯尔有限公司版权所有。
Samples of Ti-8Si, Ti-13.67Si and Ti-23S (at.%) alloys were prepared by vacuum ar melting technique and heat-treated for 2 h at 1373 K and 1473 K in a vacuum environment. The as-cast and annealed samples were examined by optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX) and hardness test. During high temperature heat-treatment, the quasi-continuous network-shaped Ti5Si3 + Ti phases in the as-cast Ti-8Si alloy finally converted to near-equiaxed Ti5Si3 grains dispersed in the Ti matrix. For Ti-13.67Si alloy, the Ti5Si3 grains finally also transformed to the near-equiaxed ones compared with the lamellar grains in the as-cast alloy. Moreover, compared with the as-cast alloy, Vickers hardness of Ti-85i and Ti-13.67Si alloys was increased by the annealing. However, the microstructure of the Ti-23Si alloy could not change significantly. So, adversely Vickers hardness decreased after high temperature heat-treatment. The microstructural evolution of Ti-Si alloys is related with the diffusion of Si atoms in the Ti/Ti5Si3 interface during high temperature heat-treatment producing as much as possible homogeneous distribution of Ti5Si3 particles in a continuous alpha-Ti matrix. The task was not achievable for Ti-23Si alloy because of the stability of the primary Ti5Si3 phase particle during heat-treatment. (C) 2009 Elsevier B.V. All rights reserved.