Powder Metallurgy of Light, Reactive and Other Non-ferrous Metals: Powder Metallurgy of Superalloys, Amorphous Metal Powder and Molybdenum-Silicon-Boron Alloy
Program Organizers: Ma Qian, Royal Melbourne Institute of Technology; Zak Fang, University of Utah; David Yan, San Jose State University; James Paramore, U.S. Army Research Laboratory
Thursday 8:00 AM
October 3, 2019
Location: Oregon Convention Center
Session Chair: Peng Yu, Southern University of Science and Technology
The Research on Improve the Mechanical Property by
Selective Formation of Y-Ti-O Complex Oxide in Ni-based ODS Alloy: Chunwoong Park1; Won June Choi1; Jong Min Byun2; Young Do Kim1; 1Hanyang University; 2Seoul National University of Science and Technology
Y2O3 is mainly applied as a dispersoid in Ni-based oxide dispersion strengthened (ODS) alloys. The added Y2O3 reacts with Ti and Al at a temperature above 1150℃ to form a complex oxides such as Y-Ti-O and Y-Al-O. However, previous studies have shown that Y-Al-O has relatively coarser particles than Y-Ti-O. In this study, Ti was first added to form Y-Ti-O, which has relatively fine particles. Subsequently, Al was added to inhibit the formation of Y-Al-O, thus improving the high-temperature mechanical properties of ODS alloys. Ni-based ODS alloy powders with composition Ni-15Cr-xTi-1.1Y2O3 were mechanically alloyed. Thereafter, the mechanically alloyed powders were heat treated to form a complex oxide of Y-Ti-O. A second mechanical alloying was performed by adding 4.5 wt.% Al to the heat treated powders. The products obtained after the second alloying were sintered by SPS. The sintered specimens analyzed using a XRD, TEM and hot hardness meter.
8:20 AM Invited
Soft Magnetic Properties of Amorphous Metal Powders Fabricated by Gas-atomization Process: Yong-Jin Kim1; Jae Won Chung1; Dong-Yeol Yang1; Sangsun Yang1; Ki Bong Kim1; Min Ha Lee2; Hwi Jun Kim2; 1Korea Institute of Materials Science; 2Korea Institute of Industrial Technology
In this work, ultra-fine soft-magnetic micro-powders are prepared by high-pressure gas atomization of amorphous alloys. Spherical powders are successfully obtained by disintegration of alloy melts under high-pressure He or N2 gas. Mean diameter of the obtained powders is 25.7 Ám and 42.1 Ám for He and N2 gas, respectively. Their crystallographic structure is confirmed to be amorphous phase throughout the interior when the particle diameter is under 45 Ám. The prepared powders show excellent soft magnetic properties with saturation magnetization of 164.5 emu/g and coercivity of 9.0 Oe. Finally, toroidal core is fabricated for the measurement of magnetic permeability, and μr up to 78.5 was obtained. It is strongly believed that soft magnetic powders prepared by gas-atomization will be highly beneficial for high-performance electromagnetic applications.
8:40 AM Invited
The Influence of Atomisation route and Powder Characteristics on the Microstructural and Mechanical Properties Development of HIPped IN625 Ni-Superalloy: Alessandro Sergi1; Alessandro Abena1; Raja Khan2; Khamis Essa1; Moataz Attallah1; 1University Of Birmingham; 2TWI Ltd
Powder characteristics and atomisation route play a crucial role in controlling the microstructural and mechanical properties development in powder hot isostatic pressing (HIPping) of Ni-superalloys. The atomisation route influences the oxygen content, morphology, and powder size distribution, with the latter influencing the packing density. In this work, the influence of the atomisation process on the microstructure and mechanical properties is assessed in HIPped IN625 by comparing water, nitrogen gas, and argon gas atomised powders. Furthermore, the influence of particle size is presented by analysing fine, coarse and wide range nitrogen gas atomised powders. To this end, a finite element model for the HIPping process was developed to determine the strain energy due to HIPping as a function of powder characteristics. Results reveals that the strain energy can be correlated to the powder packing density, which is manifested in the Σ3 special boundaries fraction generated in the HIPped microstructure.
9:00 AM Invited
Powder Processing Mo-Si-B for High Strength and Low Temperature Toughness: Peter Marshall1; Sharvan Kumar2; Xiang Yu2; 1Imaging Systems Technology; 2Brown University
Molybdenum matrix, Mo-Si-B materials are a candidate for high temperature structural applications in oxidizing environments. Powder processing has been used to produce these materials by reactions between molybdenum and the nitrides of silicon and boron with consolidation by hot isostatic pressing. Powder processing allows for a large composition design space which has been leveraged to explore the process - microstructure - properties relationship. Hot strength is provided by both secondary phases and solid solution hardening. By varying the composition and process parameters, the separation of these hardening mechanisms is possible. Further, these factors affect the fracture toughness, which is a critical aspect for candidate applications. This presentation will cover the employed powder processing as well as recent results regarding the effect of matrix fraction on hot tensile strength and solid solution upon the fracture toughness. Preliminary fracture toughness results at 300C to 800C have approached 20 MPa-m1/2.