1、0)(xC0)(xC Diffusion in single phase Diffusion in multiphasetAxCmfluxdiffusionddflowdiffusionlimdd0 xCDtAmJAxCDtmtmt界面xC2C1C2 C1，均为固定值CDCDJgradRTQDDexp0tCxJxJxJJxx0210limlimxxx+xxJxJx+x22)(xCDtCxxCtCif D=const.CDCyCxCDtC2222222zFor 3 dimensional diffusion:)z(z)()(CDyCDyxCDxtC)z(const.if222222CyCxCDt
2、CDrCrDrCDrCrrrDtC22)(rCrDrCDrCrrrDtC2)(22222112122211222)(00)(rrrrCCabracbracbracrCrrCrrrDtC2112122)(4dd4ddddrrrrCCDrCrDrCDAtmCC0CC01r2r210,tttrt增加12rr TABC0C0TC)(4)(4dd1L212112LrCCDrrrrrCCDtmootCCCCDrtrCCDrCCtrCCDrCCrrm)(2d)(d)(d)(4)(d4(dLLL211L1LL1L21LL121ExampleA 0.05cm layer of MgO is deposited
3、between layers of Ni and Ta to provide a diffusion barrier that prevents reactions between the two metals.At 1400,Ni ions are created and diffuse through the MgO ceramic to the Ta.Determine the number of nickel ions that pass through the MgO per second.The diffusion coefficient of Ni ions in MgO is 910-12cm2/s,and the lattice parameter of nickel at 1400 is 3.610-8cm.Solution32238MgO/Nicmatoms1057.8cm106.3cellunitatomsNi4Ccmcmatoms1071.105.01057.8032422xCscmatomsNi1054.1)1071.1)(109(2132412xCDJs/atomsNi1016.6221054.11313Total Ni atoms per second
