Nanocrystalline titanium produced by hydrostatic extrusion
Nanocrystalline titanium produced by hydrostatic extrusion
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DOI：
10.1016/j.jmatprotec.2007.11.103
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发表时间：
2008-08-26
影响因子：
6.3
通讯作者：
Kurzydlowski, Krzysztof J.
中科院分区：
文献类型：
--
作者：
Pachla, Wacek;Kulczyk, Mariusz;Kurzydlowski, Krzysztof J.
商业纯钛 (CP-Ti) 2 级经过 20 次连续静压挤压 (HE)，累积真应变为 5.47，无需中间退火。 HE 可显着细化晶粒。晶粒尺寸从大约33μm减小到等效晶粒直径47nm的纳米级。结构的细化伴随着机械性能的极大增强，延展性保持在其他块体严重塑性变形 (SPD) 处理材料的水平特征（类似于 8%）。 HE 后测量了极限拉伸强度 UTS > 1300 MPa 和屈服应力 YS 类似于 1250 MPa，这是迄今为止报道的大块 CP-Ti 样品的最高值。这些值高于固溶处理（硬化）Ti-Al-V 商用合金的值。 Hall-Petch (H-P) 强度和硬度关系已显示出不一致。对于 YS 依赖性，线性拟合似乎是合适的，而硬度依赖性揭示了从正（随着晶粒尺寸减小而材料硬化）到负（材料软化）的斜率变化。阈值落在类似于 120 nm 的位置，通常被认为是 UFG/NC 微观结构转变边界的点附近。所得结果揭示了使用静液压挤压（HE）工艺制造长长度高强度纳米晶 CP-Ti 半成品的可能性。此类半产品可用于医药，例如用于需要高强度和良好生物相容性的牙种植体。 (c) 2007 Elsevier B.V. 保留所有权利。
Commercial purity titanium (CP-Ti) grade 2 was hydrostatically extruded (HE) in 20 consecutive passes with cumulative true strain of 5.47 without intermediate annealing. HE results in a significant grain refinement. The grain size was reduced from similar to 33 mu m to nanometre scale of equivalent grain diameter 47 nm. The refinement of the structure was accompanied by enormous enhancement of the mechanical properties with the ductility retained at the level characteristic of other bulk severe plastic deformation (SPD) treated materials (similar to 8%). The ultimate tensile strength, UTS > 1300 MPa and yield stress, YS similar to 1250 MPa, the highest ever reported for bulk CP-Ti samples, were measured after HE. These values are higher than those of the solution treated (hardened) Ti-Al-V commercial alloy. The Hall-Petch (H-P) strength and hardness relations have shown to be not congruent. For the YS dependence the linear fit seems to be appropriate, while the hardness dependence reveals the slope change from positive (material hardening with decreasing grain size) to negative (material softening). The threshold falls at similar to 120 nm, around the point commonly considered to be the UFG/NC microstructure transformation border. The results obtained revealed the possibility fabricating long-length high strength nanocrystalline CP-Ti semi-products using the hydrostatic extrusion (HE) process. Such semi-products can be used in medicine, e.g. for dental implants, where high strength and good biocompatibility are required. (c) 2007 Elsevier B.V. All rights reserved.