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铁道科学与工程学报

JOURNAL OF RAILWAY SCIENCE AND ENGINEERING

Vol. 15    No. 6    December 2005

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Microstructural evolution during direct laser sintering of multi-component Cu-based metal powder
SHEN Yi-fu(沈以赴)1, GU Dong-dong(顾冬冬)1, WU Peng(吴 鹏)1
YANG Jia-lin(杨家林)2, WANG Yang(王 洋)2 

1. College of Materials Science and Technology, 
Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China; 
2. Institute of Machinery Manufacturing Technology, 
China Academy of Engineering Physics, Mianyang 621900, China

Abstract: A multi-component Cu-based metal powder was chosen for direct laser sintering. The powder consists of a mixture of high-purity Cu powder, pre-alloyed CuSn and CuP powder. Liquid phase sintering with complete melting of the binder (CuSn) but non-melting of the cores of structural metal (Cu) proves to be a feasible mechanism for laser sintering of this powder system. The microstructural evolution of the sintered powder with variation of laser processing parameters was presented. High sintering activities and sound densification response were obtained by optimizing the laser powers and scan speeds. Using a high laser power accompanied by a high scan speed gives rise to balling effect. At a high laser power with a slow scan speed the sintering mechanism may change into complete melting/solidification, which decreases the obtainable sintered density. The role of additive phosphorus in the laser sintering process is addressed. Phosphorus can act as a fluxing agent and has a preferential reaction with oxygen to form phosphatic slag, protecting the Cu particles from oxidation. The phosphatic slag shows a concentration along grain boundaries due to its light mass as well as the short thermal cycle of SLS.

 

Key words:  direct metal laser sintering; Cu-based metal powder; liquid phase sintering; microstructure

ISSN 1672-7029
CN 43-1423/U

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