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The effect of TLP bonding temperature on microstructural and mechanical property of joints made using FSX-414 superalloy

Bakhtiari, R ; Sharif University of Technology | 2012

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  1. Type of Document: Article
  2. DOI: 10.1016/j.msea.2012.03.073
  3. Publisher: 2012
  4. Abstract:
  5. The bonding temperature is an important parameter for optimization of the Transient Liquid Phase (TLP) bonding process in order to achieve a sound joint with good mechanical properties. However, the bonding temperature used can also be restricted by the microstructural stability of the base metal. In this study, the effect of bonding temperature (1050-1200 °C) on the joint microstructure and mechanical properties was studied for TLP bonding of FSX-414 superalloy using MBF-80 interlayer with thickness of 50 μm. Increasing bonding temperature from 1050 to 1150 °C caused reduction in the time required for complete isothermal solidification in agreement with models based on the diffusion induced solid/liquid interface motion. But even after 120. min hold time at 1200 °C, isothermal solidification was not complete and significant liquid penetration at grain boundaries adjacent to the joints was observed. Heating the base metal specimens to various temperatures of 1160-1190 °C and then water quenching, showed that 1190 °C is the critical temperature for base metal liquefaction. The maximum hardness at isothermal solidification zone and maximum hardness of phases at joint and diffusion affected zone was increased and decreased, respectively, with increasing temperature up to 1150 °C. Also, the shear strength at complete isothermal solidification was increased at the same trend. But a significant reduction in shear strength and maximum ISZ hardness were observed for sample bonded at 1200 °C. Separated bond-line and fracture surface and also cleavage-like features were seen at fracture surface of shear tested samples for this temperature which are evidences of brittle fracture
  6. Keywords:
  7. Phase transformation ; Base metals ; Bonding temperatures ; Critical temperatures ; Diffusion-affected zone ; Fracture surfaces ; Hold time ; Isothermal solidification ; Joint microstructures ; Liquid penetration ; Maximum hardness ; Mechanical characterizations ; Micro-structural ; Microstructural stability ; Solid/liquid interfaces ; TLP bonding ; Transient liquid phase bonding ; Water quenching ; Bonding ; Brittle fracture ; C (programming language) ; Electron microscopy ; Grain boundaries ; Hardness ; Isotherms ; Liquids ; Microanalysis ; Phase transitions ; Solidification ; Superalloys
  8. Source: Materials Science and Engineering A ; Volume 546 , June , 2012 , Pages 291-300 ; 09215093 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0921509312004431