激光多层熔覆沉积预混合Ti-xAl-yV合金粉末在熔池中的熔化与偏析行为

陈静; 张凤英; 谭华; 林鑫; 黄卫东

doi:doi:10.3788/cjl20103708.2154

中国激光, 2010, 37 (8): 2154, 网络出版: 2010-08-13

激光多层熔覆沉积预混合Ti-xAl-yV合金粉末在熔池中的熔化与偏析行为

Alloying Mechanics in Moving Melt Pool during Laser Solid Forming from Blended Elemental Powders

论文大纲

陈静 ^*张凤英谭华林鑫黄卫东

作者单位

西北工业大学凝固技术国家重点实验室,陕西西安 710072

激光技术激光立体成形混合元素粉末钛合金熔池合金化 laser technique laser solid forming blended elemental powders titanium alloy melt pool alloying

摘要

研究了混合元素法激光立体成形(LSF)钛合金,结合激光熔池内粉末颗粒熔化时间的计算以及熔池固液界面运动分析,揭示了混合元素法激光立体成形熔覆层内未熔粉末颗粒的形成机理,即元素粉末颗粒进入激光熔池内的“不熔区”是导致合金熔覆层内产生未熔粉末颗粒的根本原因。熔覆材料为球形时,未熔粉末颗粒呈“月牙”形或球形,实验观察结果与理论分析吻合很好。进一步研究了Ti-xAl-yV合金熔覆层内成分偏析带的形貌特征及产生条件:元素V含量较高时,Ti-xAl-yV合金熔覆层内易产生规律分布的成分偏析带,这是由于激光熔池内固液界面前沿熔体流动速度过低、合金化不充分而导致的。通过控制粉末输送参数、粉末性质参数和成形工艺条件,能够获得成分均匀的合金熔覆层。

Abstract

The laser solid forming (LSF) titanium alloys from blended elemental powders are investigated. By combining the computation of the melting time of powder particles with the motion analysis of the solid-liquid interface of the melt pool,the formation mechanism of the unmelted powder particles during LSF from blended elemental powders is disclosed. That the powder particles inject into the "unmelted zone" is the main reason leading to the formation of the unmelted particles. The morphologies of the unmelted particles are presented as "crescent" or sphere when the spherical elemental powder particles are used as the deposited materials. The theoretical analysis agrees well with the experimental results. The morphology and formation condition of the composition segregation band during LSF Ti-xAl-yV from blended elemental powders are investigated. It is found that the composition segregation band is prone to occur when the V content in the Ti-xAl-yV alloys is near or higher than the critical concentration of element V,and this is caused by the low melt flow velocity near the solid-liquid interface in the melt pool. The uniform composition in the alloying clad layers can be obtained by controlling the powder delivery parameters,powder characteristics,and the processing parameters.

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陈静, 张凤英, 谭华, 林鑫, 黄卫东. 激光多层熔覆沉积预混合Ti-xAl-yV合金粉末在熔池中的熔化与偏析行为[J]. 中国激光, 2010, 37(8): 2154. Chen Jing, Zhang Fengying, Tan Hua, Lin Xin, Huang Weidong. Alloying Mechanics in Moving Melt Pool during Laser Solid Forming from Blended Elemental Powders[J]. Chinese Journal of Lasers, 2010, 37(8): 2154.

激光多层熔覆沉积预混合Ti-xAl-yV合金粉末在熔池中的熔化与偏析行为

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