Solid State Diffusion Bonding of Metals and Alloys: Solid State Diffusion Bonding of Metals and Alloys III
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Advanced Characterization, Testing, and Simulation Committee
Program Organizers: Mohamed Elbakhshwan, University of Wisconsin Madison; Mark Anderson, University of Wisconsin Madison; Todd Allen, University of Michigan ; Tasnim Hassan, North Carolina State University
Tuesday 8:30 AM
February 25, 2020
Room: 19
Location: San Diego Convention Ctr
Session Chair: Mohamed Elbakhshwan, UW-Madison; Tasnim Hassan, North Carolina State University; Heramb Mahajan, North Carolina State University
8:30 AM Invited
Multi-Scale Study Of Bonding Mechanism Between Immiscible Mg/Steel Alloys: Jiahao Cheng1; Xiaohua Hu2; Xin Sun2; Vivek Anupam3; Glenn Daehn3; David Cullen3; 1Oak Ridge National Laboratory; 2Oak Ridge National Laboratory; 3The Ohio State University
Vaporizing foil actuator spot welding method is used to join magnesium alloy AZ31 and uncoated high-strength-steel DP590, which are typically considered as unweldable due to high physical property disparities, low mutual solubility, and none-existence of intermetallic phases. SEM and HRTEM characterization of the weld interface found the impact creates an Mg nanocrystalline inter-lay with abundant Fe particles. The inter-lay exhibits intact bonding with both DP590 and AZ31 substrates. To understand the underlying mechanisms, finite element-based process simulation and subsequent molecular dynamics (MD) simulations are conducted to study the impact and cooling processes at different location of the interface. The results found the inter-layer formation is through impact induced mechanical “mixing”, and segregation of Fe atoms during the rapid cooling. At last, MD simulation compares the impact-induced immiscible materials interface with DC resistance spot welding induced interface, explaining the difference in the bond strength anticipated for the different joining methods.
9:00 AM
The Role of Interface Microstructure and Chemistry on the Bond Strength of Aluminum 6061 HIP-bonded Samples: Rajib Kalsar1; Brady McBride2; Rick Shimskey1; Kester Clarke1; Nicole Overman1; Curt Lavender1; Kenneth Johnson1; Vineet Joshi1; 1Pacific Northwest National Laboratory; 2Colorado School of Mines
Low-enriched uranium (LEU) alloyed with 10 wt% molybdenum (U-10Mo) has been identified as a promising alternative to high-enriched uranium (HEU) for the United States High Performance Research Reactors (USHPRR). The nominal configuration of the U-10Mo plate-type fuel is a metallic U-10Mo fuel foil, the thickness of which varies from 0.6 mm (0.025") to 0.2 mm (0.0085") depending on the reactor; a 25 μm thick Zr interlayer–diffusion barrier on either side, and an outer cladding of 6061 aluminum. The aluminum cladding is usually performed using the HIP process. In the present work, the role of interface microstructure and chemistry on the bond strength of Al-6061 alloy bonded by hot isostatic pressing (HIP) was investigated. The impact of different HIP parameters such as temperature, surface preparation, surface texture and strong-back materials on bond strength was investigated. Interface microstructures were characterized to quantify the oxide layer thickness, Mg2Si fraction and interface recrystallization.
9:20 AM
Microstructural Evolution and Mechanical Properties of Lap-jointed Ti-6Al-4V Plates by Pin-less Friction Stir Spot Welding: Hyojin Park1; Yong Chae Lim2; Hahn Choo1; Suhong Zhang1; Anming Hu1; Scott A Rose3; Zhili Feng2; 1University of Tennessee, Knoxville; 2Oak Ridge National Laboratory; 3Boeing
Ti-6Al-4V has excellent mechanical properties and corrosion resistance that will be attractive for aerospace applications. However, very limited researches have been conducted for joining of titanium alloys using a solid-state welding process. In the present work, we applied a novel pinless friction stir spot welding technique to spot join Ti-6Al-4V sheets with a lap joint configuration. Frictional heat generated underneath of flat tool diffused into the interface of two titanium sheets and finally produced solid-state bonding. Various welding parameters were applied and evolution of metallurgical bonding size at joint interface was measured from cross-sectional view. Microhardness on the welded samples were measured and correlated with microstructures. Mechanical lap shear tensile testing was conducted to assess the bonding strength of Ti-6Al-4V specimens. Finally, the boding mechanism is discussed based on solid state diffusion.
9:40 AM
MTI Low Force Friction Welding: Simon Jones1; 1MTI
The benefits of low force welding over traditional fusion/solid-state bonding processes and its potential future applications. This presentation provides an up to date overview of the Low Force welding process development conducted by MTI adopting linear and reciprocating relative motion with inductive and resistance preheating. Multiple Aerospace materials have been evaluated during this multi-year development program. The data acquired during the weld development program has constructed a comprehensive understanding of how weld parameters relate to the post weld mechanical performance of the resultant bond. This data is also drawn upon to design parameter sets that produce welds with tailored characteristics specific to a desired performance or application. The presentation includes an assessment of key issues associated with traditional welding processes and how Low Force Technology can alleviate these by exploiting the positive attributes of fusion and solid state joining and combining them to form a single process.
10:00 AM Break
10:30 AM
Instant Copper Direct Bonding Using <111>-oriented Nanotwinned Cu Microbumps: Kai-Cheng Shie1; Jing-Ye Juang1; Chih Chen1; 1National Chiao Tung University
Ultra-fine pitch (under 10 um) interconnects are needed for high performance chips, such as high computing chips. Copper direct bonding technology is the solution of this application in the future. This study uses semiconductor manufacturing processes to fabricate top dies and bottom dies with resistance test vehicles. The test dies have arrays of <111>-oriented nanotwinned Cu (nt-Cu) microbumps. With about 40 % <111>-oriented Cu surface, Cu direct bonding can successfully achieve in 5 s with 300 ℃ and 90 MPa bonding pressure in N2 ambient. The pressure can lower to 30 MPa and bond in 10 s, too. The resistance of a single bump is about 4.8 mohm using Kelvin probes. The microstructures be analyzed systematically by FIB and EBSD. The instant bonding processes may provide a solution for chip to chip and chip to wafer bonding.
10:50 AM
Mechanical Performance of Diffusion Bonded 316 Stainless Steel for use in a Hybrid Compact Heat Exchanger: Kyle Rozman1; Venkata Saranam2; Brian Paul2; Ömer Doğan1; 1National Energy Technology Laboratory; 2Oregon State University
Hybrid compact heat exchangers have been proposed to handle the high-pressure differentials between liquid sodium coolant in fast reactors and supercritical CO2 in Brayton power cycles for electric power generation. However, their use has not been certified. A candidate material for manufacturing these hybrid compact heat exchangers is 316 stainless steel, which has been proven corrosion and creep resistant up to 550oC in both sodium and supercritical CO2 environments. The authors present room and elevated temperature mechanical performance of diffusion bonded 316, including tensile, creep and creep fatigue results. These results are discussed in context of use for a hybrid compact heat exchanger.