Tested 30Fe-70La alloy is melted by a high frequency suspending melting furnace and cut to 8 mm x 8 mm x6 mm specimen and butted on same size pure iron specimen

then the diffusion test is carried out at 10

-3

Pa vacuum and 1 MPa pressure at 760℃ and 770℃ 30 min by Gleeble-1500D hot simulation experiment machine； the diffusion of rare earth element lanthanum in Fe matrix is observed by Axiovert 25 optical microscope and QUANTA 400 environmental scanning electron microscope

and the diffusion coefficient of lanthanum in pure iron is calculated by relative diffusion coefficient formulas. Results show that the diffusion of rare earth element lanthanum in pure iron is carried out along a-Fe grain boundaries

and the diffusion coefficient Db of lanthanum in grain boundaries of pure iron ferrite is 1. 59 x 10

-17

m

2

/s.