Mechanical performance and microstructural characterisation of titanium alloy-alloy composites built by wire-arc additive manufacture
Mechanical performance and microstructural characterisation of titanium alloy-alloy composites built by wire-arc additive manufacture
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DOI：
10.1016/j.msea.2019.138289
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发表时间：
2019-09-23
期刊：
影响因子：
6.4
通讯作者：
Prangnell, P. B.
中科院分区：
文献类型：
--
作者：
Davis, A. E.;Breheny, C., I;Prangnell, P. B.
第一阶段的研究已经进行了调查的潜力，利用高沉积速率WAAM打印双合金微观结构。使用商业纯Ti和Ti-6Al-4V的交替进给丝构建样品。在沉积过程中发生高水平的稀释，伴随着有效的液相混合，产生规则分布的近似双峰组合物的固化的熔体轨道，每个不太极端比它们各自的组成进料线。双合金复合材料的屈服强度大约在生产它的两种合金的屈服强度之间，并表现出双拐点屈服行为。总的来说，由于相对粗糙的长度尺度，在拉伸载荷中没有比化学均质材料的拉伸载荷更显著的性能优势，因此在该长度尺度下打印替代合金的主要优势可能更多地存在于断裂或疲劳载荷期间增加的裂纹路径曲折度。重要的是，沉积的材料被发现具有细化的β-晶粒结构，这表明由双合金印刷引入的组成梯度可以破坏通常在WAAM沉积物中看到的外延柱状生长。
A first stage study has been performed to investigate the potential for exploiting high deposition rate WAAM to print dual-alloy microstructures. Samples were built using alternating feed wires of commercially-pure Ti and Ti-6Al-4V. A high level of dilution occurred during deposition accompanied by effective liquid-phase mixing, producing a regular distribution of solidified melt tracks of approximate bimodal composition each less extreme than that of their respective constituent feed wires. The yield strength of the dual alloy composite material was approximately midway between that of the two alloys from which it was produced and exhibited a double inflection yield behaviour. Overall, because of the relatively coarse length scale there was not a significant property advantage in tensile loading above that of a chemically homogenous material, thus the main advantage of printing alternate alloys at this length scale is likely to reside more with increasing crack path tortuosity during fracture or fatigue loading. Importantly, the deposited material was found to have a refined beta-grain structure suggesting that the composition gradients introduced by dual-alloy printing can disrupt the epitaxial columnar growth normally seen in WAAM deposits.