The reaction between salt fluxes containing metal fluorides and main elements in A356 alloy was investigated by thermodynamics analysis and experiments

and its influence on microstructure and constituent of Al alloy and the phase of fluxes were analyzed by SEM

EDS and XRD.The results reveal that the equilibrium constants of displacement reactions between main elements of A356 alloy and metal chlorides are mostly lower than those of metal fluorides

which indicate that metal chlorides are more stable than fluorides in salt fluxes.NaF

SrF

2

and BaF

2

in the fluxes can react easily with Al or Mg and generate the divorced atoms in Al melt

such as Na

Sr

Ba

to modify eutectic silicon significantly.Na3 AlF6 fluxes can also react with Al and generate trace the divorced Na atoms to modify eutectic silicon slightly.However

influences of AlF

3

MgF

2

and CaF

2

on microstructures of A356 alloy can be ignored.Metal fluorides not exhibit measurable effects on the phase of salt fluxes while NaF and BaF

2

can generate new phases KMgF

3

and BaFCl in salt fluxes

respectively.MgF

2

CaF

2

SrF

2

BaF

2

would remain in A356 alloy because of their high densities and melting points

which could affect the constituents of alloy.