Dear all,

美國加州大學大學材料系教授杜經寧院士將於6/22(一) 到訪本系

屆時將於10:00-11:30 am 在工科館205室進行專題演講，歡迎各位的參加

講題為:

Chemical effect on interdiffusion and reaction to form intermetallic compounds in bi-metallic systems

K. N. Tu, Dept. of Materials Science and Engineering, UCLA

Abstract:  In the classical Darken’s analysis of interdiffusion in forming an alloy, ideal solution was assumed so chemical effect could be ignored.  If a regular solution (chemical effect) is taken, the well-known thermodynamic factor of (1 + dlnϒ/dlnX) is introduced to modify the interdiffusivity.   When we study intermetallic compound (IMC) formation, say between Ni and Sn or between Cu and Sn, clearly there is a strong chemical effect.  However, while many data on interdiffusion in IMC were obtained, no chemical effect or the thermodynamic factor has been included.  In this talk, we shall introduce Wagner’s diffusivity, which is a product of ∆C, where is interdiffusivity and ∆C is the concentration difference across the near-stoichiometric IMC layer.  We note that the ∆C is unmeasurable, yet the product is measurable.  Hence, we are able to combine it with marker motion to unravel the intrinsic diffusivities, say Ni and Sn in a compound of Ni₃Sn₄.