A novel yielding anisotropy and corresponding lattice evolution mechanism in CP-Ti achieved via pulsed electric current
A novel yielding anisotropy and corresponding lattice evolution mechanism in CP-Ti achieved via pulsed electric current
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DOI：
10.1016/j.matdes.2021.110013
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发表时间：
2021-11
影响因子：
8.4
通讯作者：
T. Chen;J. A. Lin;W. Cai;Hongwei Ma;L. H. Liu;Zhuolin Wang;C. Yang
中科院分区：
文献类型：
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作者：
T. Chen;J. A. Lin;W. Cai;Hongwei Ma;L. H. Liu;Zhuolin Wang;C. Yang
我们报告了商业纯钛（CP-Ti）中一种新颖的屈服各向异性，并提供了对其织构演化和相应晶格演化机制的基本见解。在此，通过脉冲电流（PEC）进行α↔β循环相变（CPT）处理来获得各向异性。经过三循环CPT处理后，垂直于PEC方向的CP-Ti在X射线衍射强度中表现出(0002)面的最大值，并且在电子背散射衍射分析中表现出{0001}极图。经过三循环处理的 CP-Ti 呈现出显着的屈服各向异性，其屈服强度 (297.5 MPa) 远高于其他处理过的试样。这归因于三循环处理的 CP-Ti 中优先激活的基底滑移具有更高的有效临界解析剪切应力，而其他处理的样本则优先激活棱柱滑移。从根本上来说，提出了导致这种产生各向异性的晶格演化机制和取向关系（{0001} α//{001} β 和< 11 2´ 0> α//< 1´ 00> β）。在PEC下，HCP结构中的(0001)面平行于BCC结构中的(001)面转变，并且当PEC关闭时，在冷却下BCC中的(110)面随后转变为HCP中的(0001)面。
We report a novel yielding anisotropy in commercially pure titanium (CP-Ti) and provide fundamental insights into its texture evolution and the corresponding lattice evolution mechanism. Herein, yielding anisotropy was attained by an α↔ β cyclic phase transformation (CPT) treatment via pulsed electric current (PEC). After the three-cycle CPT treatment, the CP-Ti perpendicular to the PEC direction exhibited the maximum value of (0002) plane in the X-ray diffraction intensity and of {0001} pole figure for electron backscatter diffraction analysis. The three-cycle-treated CP-Ti presented a significant yielding anisotropy which was the far greater yield strength (297.5 MPa) than that of the other treated specimens. This is attributed to the preferential activation of basal slip with a higher effective critical resolved shear stress in the three-cycle-treated CP-Ti, compared with the preferential activation of prismatic slip for the other treated specimens. Fundamentally, the lattice evolution mechanism and orientation relationship ({0001} α//{001} β and< 11 2¯ 0> α//< 1¯ 00> β) responsible for this yielding anisotropy were proposed. Under the PEC, the (0001) plane in HCP structure transformed in parallel to the (001) plane in BCC structure, and followed by the transformation of the (110) plane in the BCC to the (0001) plane in the HCP under cooling when the PEC was switched off.