选区激光熔化不同层厚镍的热特性与机械性能  

Thermal Properties and Mechanical Properties of Selective Laser Melting Different Layer Thicknesses of Ni Powder

作　　者：闫岸如[1] 杨恬恬[1] 王燕灵[1] 马志红 杜云 王智勇[1] 

机构地区：[1]北京工业大学激光工程研究院,北京100124 [2]成都三鼎日新激光科技有限公司,四川成都610000

出　　处：《中国激光》2016年第2期68-76,共9页Chinese Journal of Lasers

基　　金：国家科技重大专项(2010ZX04013-052)

摘　　要：为解决商用选区激光熔化设备制作散热器生产效率低的问题并使之保持良好的散热特性与机械性能,采用纯Ni粉末进行不同层厚选区激光熔化成形获得了高效制作、性能良好的样品。从致密度、金相显微组织、热特性、机械性能等方面展开研究,一定范围内增加层厚能够提高成形效率并且保证成形样品的热特性与机械性能。超过激光可烧结的层厚阈值时,烧结轨迹为球化线。在可烧结层厚范围内,改变工艺参数能使成形体均接近完全致密。层厚由20μm增加至40μm,初始枝晶间距由305 nm增至639 nm。热导率由20μm时的99.28 W/K·m降低至40μm成形时的92.48 W/K·m。25℃~100℃时,40μm层厚成形体热膨胀系数由11.02×10^(-6)m/(m·℃)升至12.9×10^(-6)m/(m·℃),低于对应温度区间内20μm层厚成形体热膨胀系数由11.42×10^(-6)m/(m·℃)升至13.4×10^(-6)m/(m·℃)。20μm层厚与40μm层厚成形试样的拉伸强度均远高于国标锻压件。应用选区激光熔化技术成形散热器,采用40μm层厚成形的生产效率比20μm层厚成形提高34.6%。In order to solve the problem of low production efficiency in making heat sink use the commercial selected laser melting （SLM） equipment while keeping good thermal properties and mechanical properties, SLM technology is used to build Ni samples with different （20/40/60 μm ） powder layer thicknesses. The relative density, microstructure, thermal conductivity, thermal expansion coefficient and tensile properties of the samples are presented. Beyond the layer thickness threshold of the laser melting, the melting track is spheroidizing line. Within the layer thickness range can be melted, the samples can be nearly full densification. With increasing layer thickness from 20 μm to 40 μm, the primary dendrite spacing increases from about 347 nm to 635 nm. Thermal conductivity decreasing from 99.28 W/K- m at 20 μm to 92.48 W/K. m at 40 μm. Increasing from 25 ℃ to 100 ℃ the thermal expansion coefficient from 11.02× 10-6 m/（m. ℃） to 12.9×10-6 m/（m. ℃ ） at 40 ~m layer thickness, lower than 11.42× 10-6 m/（m. ℃） to 13.4×10-6 m/（m. ℃） at 20 μm. Tensile strengths of SLMed Ni samples are much higher than those of wrought Ni regardless of layer thickness and building direction. The production efficiency of using SLM technology form heat sink at 40 μm increases 34.6% compared with 20 μm.

关 键 词：材料 选区激光熔化 生产效率 不同层厚 热特性 机械性能 

分 类 号：TG115.2[金属学及工艺—物理冶金]