Microstructure and tensile properties of superalloy IN100 fabricated by micro-laser aided additive manufacturing

作者：Bi Guijun^*; Sun Chen Nan; Chen Hui chi; Ng Fern Lan; Ma Cho Cho Khin

来源：Materials & Design, 2014, 60: 401-408.

DOI：10.1016/j.matdes.2014.04.020

• Micro-laser aided additive manufacturing
• Ni-base superalloys
• Microstructure
• Grain boundaries
• Electron backscatter diffraction
• Tensile properties

Layer by layer fabrication using micro-laser aided additive manufacturing (micro-LAAM) was successfully implemented on nickel-base superalloy IN100. It is known that IN100, a type of superalloy having high titanium and aluminum contents, has poor weldability due to weld liquation cracking in the heat-affected zone (HAZ) and strain age cracking. In this study, micro-LAAM process was optimized through a set of designed experiments to eliminate crack formation and reduce porosity. It was found that the crack-free deposition can be achieved owing to the fact that micro-LAAM process used in this study had very low heat input. Three distinct sizes of gamma ' precipitates were observed on the post heat-treated samples. The volume fractions of gamma to gamma ' phases were found to be approximately 60-40%. Microstructure and chemical analysis results showed that gamma ' phase was embedded within gamma-Ni matrix while various carbides (MC, M23C6 and M6C) were observed as precipitates at grain boundaries or within grains. Electron backscatter diffraction (EBSD) was used to compare grain morphologies and size distribution of three distinctly different regions on each layer. The achieved ultimate tensile strength and yield strength are much better than the minimum requirements specified in aerospace material specification 5397 for cast IN100.

• 出版日期2014-8