Novel powder packing theory with bimodal particle size distribution-application in superalloy

• Published in: Advanced powder technology : the international journal of the Society of Powder Technology, Japan Japan, 2018-09, Vol.29 (9), p.2280-2287
• Main Authors: Ye, Xianjue, Li, Yunping, Ai, Yanling, Nie, Yan
• Format: Article
• Language: English
• Subjects: Packing density theory; Powder metallurgy; Sintering; Superalloy
• ISSN: 0921-8831; 1568-5527
• DOI: 10.1016/j.apt.2018.06.012

Schematic illustration of powder packing of powder with a bi-model particle size distribution and the resultant sintered microstructure [Display omitted] •The sintering ability of powder is related to the powder packing density.•The second-order powder packing theory is proposed.•Sintering ability of powder is enhanced by optimized particle size distribution.•The experiment results are consistent with the proposed theory. Powder packing behavior plays an important role in determining sintering ability of powder and the resultant performance of materials. In this study, a novel powder packing theory with bimodal particle size distribution is proposed by considering the loosening effect, wall effect and wedging effect. This theory is applied in PM nickel base superalloy by using mixture of coarse particles and fine particles. Microstructures of alloy sintered by vacuum hot pressing (HP) are observed by optical microscope (OM) and electron backscatter diffraction (EBSD). The prediction result by this theory is in good agreement with the experimental results. The enhanced sintering ability of powder containing appropriate fractions of coarse particle and fine particle is ascribed to the filling of fine particles to the voids between coarse particles, which enhanced the density of sample after sintering. Tensile behavior and the fracture morphology of alloys with various particle distributions are analyzed in details, suggesting the higher reliability of the present theory.