Copper-based alloys

CALPHAD based software and databases allow for accurate calculations of phase equilibria in multicomponent Cu-based alloy systems and provide a useful way to design structure and functional copper-based alloys.

In order to develop Cu-based alloys more efficiently, reliable predications of liquidus, phase fraction, equilibrium and non-equilibrium solidification behaviour, etc., in multi-component systems are required. By using Thermo-Calc and compatible thermodynamic databases, a vast amount of information can be obtained of relevance for multi-component Cu-based alloys.

Examples of what can be predicted:

  • Transformation temperatures, such as liquidus, solidus, etc.
  • Isothermal or vertical section phase diagrams
  • Amount and constitution of equilibrium phases
  • Scheil-Gulliver non-equilibrium solidification paths
  • Thermochemical properties, such as enthalpy, heat capacity, driving force for phase nucleation and growth
  • Thermophysical properties, such as volume, density and thermal expansion

By using the Diffusion module (DICTRA) and combining both thermodynamic and kinetic databases, typical diffusion-controlled phase transformations in Cu-alloys can be simulated.

Further examples using  the Diffusion module (DICTRA):

  • Microsegregation during solidification
  • Homogenization during heat treatments
  • Cooling effects in solidification
  • Growth or dissolution of intermetallic phases

By using the Precipitation module (TC-PRISMA) and combining thermodynamic and kinetic databases, the concurrent nucleation, growth and coarsening of precipitates can be simulated.

Examples related to precipitation modelling using the Precipitation module (TC-PRISMA):

  • Concurrent nucleation, growth/dissolution and coarsening of precipitates
  • Average particle radius and number density
  • Volume fraction and composition of precipitates
  • Nucleation rate and coarsening rate
  • Estimation of multicomponent interfacial energy

Paper available for download: "Kinetic Simulations of Diffusion-Controlled Phase Transformations in Cu-Based Alloys"

Click here to access a copy of this publication.

Tang, Ying, Qing Chen, and Anders Engström. 2018. “Kinetic Simulations of Diffusion-Controlled Phase Transformations in Cu-Based Alloys.” Diffusion Foundations 15: 1–22. doi:10.4028/www.scientific.net/DF.15.1.

Abstract

In this chapter, we present kinetic simulations of diffusion-controlled phase transformations in Cu-based alloys by using our most recently developed atomic mobility database (MOBCU) for copper alloys. This database consists of 29 elements including most common ones for industrial copper alloys. It contains descriptions for both the liquid and Fcc_A1 phases. The database was developed through a hybrid CALPHAD approach based on experiments, first-principles calculations, and empirical rules. We demonstrate that by coupling the created mobility database with the existing compatible thermodynamic database (TCCU), all kinds of diffusivities in both solid solution and liquid phases in Cu-based alloys can be readily calculated. Furthermore, we have applied the combination of MOBCU and TCCU to simulate diffusion-controlled phenomena, such as solidification, nucleation, growth, and coarsening of precipitates by using the kinetic modules (DICTRA and TC-PRISMA) in the Thermo-Calc software package. Many examples of simulations for different alloys are shown and compared with experimental observations. The remarkable agreements between calculation and experimental results suggest that the atomic mobilities for Cu-based alloys have been satisfactorily described. This newly developed mobility database is expected to be continuously improved and extended in future and will provide fundamental kinetic data for computer-aided design of copper base alloys.