Microstructure and mechanical properties of Ti-2Al alloyed with Mo formed in laser additive manufacture
Microstructure and mechanical properties of Ti-2Al alloyed with Mo formed in laser additive manufacture
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DOI：
10.1016/j.jallcom.2017.07.324
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发表时间：
2017-12
影响因子：
6.2
通讯作者：
Fengying Zhang;Meng Yang;A. Clare;Xin Lin;H. Tan;Yongnan Chen
中科院分区：
文献类型：
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作者：
Fengying Zhang;Meng Yang;A. Clare;Xin Lin;H. Tan;Yongnan Chen
以Ti、Al和Mo元素粉末为原料，采用激光立体成形技术制备了一系列Ti-2Al-yMo（y= 2，5，7，9，12）合金试样。研究了β稳定剂Mo对Ti-2Al-yMo合金在指定激光工艺参数下的晶粒形貌、α板条的尺寸和分布、维氏硬度和拉伸性能的影响。结果表明，Ti-2Al-5 Mo、Ti-2Al-7 Mo、Ti-2Al-9 Mo和Ti-2Al-12 Mo合金沉积层的显微组织均由不规则柱状晶组成，柱状晶以外延方式生长，在沉积层的上部还存在一些细小的等轴晶，而Ti-2Al-2 Mo合金沉积层的显微组织则由粗大的柱状晶组成。随着Mo含量的增加，晶粒尺寸减小，等轴晶层厚度增加。这表明随着Mo的增加，柱状晶向等轴晶转变的趋势。主要β晶粒形成由初生α板条、次生α板条和残余β相组成的网篮状组织。随着Mo含量的增加，初生α板条和二次α板条的尺寸均显著减小，而二次α板条的数量急剧增加，Ti-2Al-12 Mo合金也由α相和β相组成。Ti-2Al-7 Mo、Ti-2Al-9 Mo和Ti-2Al-12 Mo的杨氏模量在实验误差范围内基本相同。试样的拉伸测试表明，Ti-2Al-7 Mo具有良好的强度和断裂延伸率组合。因此，这种材料可以被认为适合作为激光增材制造的可行原料。
A series of Ti-2Al-yMo (y= 2,5,7,9,12) alloy samples were produced from blended elemental Ti, Al and Mo powders using the laser solid forming technology. The influence of the β stabilizer Mo on the morphology of the grains, the size and the distribution of the α laths, the Vickers hardness and the tensile properties of Ti-2Al-yMo alloys were explored under designated laser processing parameters. It was found that the microstructure in Ti-2Al-5Mo, Ti-2Al-7Mo, Ti-2Al-9Mo, and Ti-2Al-12Mo deposited layers were composed of irregular columnar grains that grow epitaxially, with some small equiaxed grains in the upper region, while that of the Ti-2Al-2Mo alloy was composed of large columnar grains. The grain size decreased, while the thickness of equiaxed grains layer increased with increasing Mo content. This indicates a tendency towards columnar-to-equiaxed transition with increasing Mo. The dominant β grains form a basketweave microstructure composed of primary α laths, secondary α laths and retained β phase. It was also observed that with increasing Mo content, both the size of primary α laths and secondary α laths decreased significantly, while the number of secondary α laths increased sharply, and the Ti-2Al-12Mo is also constituted of α phase and β phase. The Young's modulus of Ti-2Al-7Mo, Ti-2Al-9Mo, and Ti-2Al-12Mo were basically the same within experimental error. Tensile testing of the specimens showed that Ti-2Al-7Mo exhibits a good combination of strength and elongation to failure. As a result, this material can be considered suitable as a viable feedstock for laser additive manufacturing.