Study of high temperature wetting and infiltration for optimising liquid phase sintering in low alloy steels

Abstract

Liquid phase sintering is commonly used in powder metallurgy to improve physical properties through densification enhancement. With the aim of combining the advantages of liquid phase sintering and the use of promising alloying elements such as Mn and Si, liquid promoters with complex compositions were designed to provide a low melting point to form a liquid phase below the common sintering temperatures. The properties of these liquid phases were characterised in terms of contact angle, spreading evolution and infiltration. Using a Krüss drop shape analysis system, both wetting angle experiments and infiltration experiments were performed by changing the substrate characteristics from sintered to green iron specimens respectively. The discussion is based on the different features found for these liquids compared with copper, which is a well known liquid phase former used for improving the properties of low alloy steels. Simulations of the thermodynamic and kinetic processes taking place were performed by combining ThermoCalc and DICTRA software analysis.

Keywords:

• Dissolutive wetting
• Infiltration
• Liquid phase sintering
• Low alloy steels
• DICTRA
• ThermoCalc

Acknowledgements

The support provided by Höganäs AB in the development of this work is gratefully acknowledged. The authors also wish to thank Dr A. Muñoz at the Department of Physics, Carlos III University, for his assistance in melting the prototypes.