Mass transport caused by buoyancy convection in front of the solid–liquid interface was evaluated in terms of measurements of primary dendritic spacing combining with separation of the effective (or integral) mass transport coefficientDL.It was shown thatDLin normal gravity (1g) condition was 1.64 times as high as that in microgravity (&mgr;g) condition at the cooling rate(v)of 0.056 K/s forPd40Ni40P20alloy. The higherDLvalue is due to the contribution of buoyancy convection on the ground. ©1997 American Institute of Physics.