三维原子探针应用(Application+of+Atom+Probe+Tomography+for+understanding+Nanostructure).ppt

* Significant solute clustering is highlighted by compensating for what occurs stochastically in a random configuration, i.e. experimental minus random. The extent of Cu-Mg clustering after 60s ageing at 150oC in the 1.7Mg alloy is observed in the lower graph because the (Exp-Ran) value is large and positive, and there is a large cluster size distribution. GBP, solute clusters and S phase particle dominate the precipitate microstructure of the alloy aged at 170 C for 80 h (with the peak hardness). Si distribution within each S-phase particle is not uniform. S-phase particles contain linear Si-rich regions, with Si concentration and size ( in diameter) similar to the values measured from GPB zones. Frequently, the attachment of GPB rods with each other and small solute clusters, and the attachment of S phase particles with several GPB rods on its surface were observed in the precipitate microstructure after careful examination of the analysed volume in three dimension, as typically shown in the next slid. This indicates that coalescence of GP zones and solute clusters is responsible for GPB zones growth, and coalescence of GPB zones are responsible formation and growth of S-phase. * * * * * * * * * F357 without natural pre-ageing * 180oC for 1 h 180oC for 4 h 10 mins WITHOUT A NATURAL PRE-AGEING Mg atom maps OF THE ALLOY experienced 120 h natural pre-ageing * 20 nm 180oC for 0 h 10 min 1 h 4 h 10 min 1h WITH 120 H NATURAL PRE-AGEING 4 h WITHOUT A NATURAL PRE-AGEING 180oC for 1 h * N=20 N=100 N=800 Number density evolutions * clusters GP zones ??? With pre-T4 treatment Without pre-T4 treatment The effect on Mg/Si ratio of solute nanostructures * * The effect on Cu concentration of solute nanostructures The effect on solute concentration reduction of the matrix * As-quenched T4 Summary ii * A combination of TEM and APT analysis helps to understand the effect of pre-natural ageing treatment at RT on solute nanostructure formation and age-hardening response