Atom probe tomographic studies of precipitation in Al-0.1Zr-0.1Ti (at.%) alloys

作者：Knipling Keith E^*; Dunand David C; Seidman David N

来源：Microscopy and Microanalysis, 2007, 13(6): 503-516.

DOI：10.1017/S1431927607070882

• atom probe tomography
• Al(3)Zr precipitates
• local magnification
• Al-Zr-Ti

Atom probe tomography was utilized to measure directly the chemical compositions of Al(3)(Zr(1-x)Ti(x)) precipitates with a metastable L1(2) structure formed in Al-0.1Zr-0.1Ti (at.%) alloys upon aging at 375 degrees C or 425 degrees C. The alloys exhibit an inhomogeneous distribution of Al(3)(Zr(1-x)Ti(x)) precipitates, as a result of a nonuniform dendritic distribution of solute atoms after casting. At these aging temperatures, the Zr:Ti atomic ratio in the precipitates is about 10 and 5, respectively, indicating that Ti remains mainly in solid solution rather than partitioning to the Al(3)(Zr(1-x)Ti(x)) precipitates. This is interpreted as being due to the very small diffusivity of Ti in a-At, consistent with prior studies on Al-Sc-Ti and Al-Sc-Zr alloys, where the slower diffusing Zr and Ti atoms make up a small fraction of the Al(3) (Sc(1-x)Ti(x)/Zr(x)) precipitates. Unlike those alloys, however, the present Al-Zr-Ti alloys exhibit no interfacial segregation of Ti at the matrix/precipitate heterophase interface, a result that may be affected by a significant disparity in the evaporation fields of the alpha-Al matrix and Al(3)(Zr(1-x)Ti(x)) precipitates and/or a lack of local thermodynamic equilibrium at the interface.

• 出版日期2007-12
• 单位西北大学