Static and in situ TEM investigation of phase relationships, phase dissolution, and interface motion in Ag-Au-Cu alloy nanoparticles

Journal Article · Mon Jun 07 04:00:00 EDT 2004 · Acta Materialia

DOI:https://doi.org/10.1016/j.actamat.2004.02.038· OSTI ID:20634700

Chatterjee, K; Howe, J M; Johnson, W C; Murayama, M

Ternary nanoparticles of Ag-Au-Cu alloy were fabricated by physical vapor deposition of a ternary alloy source onto a heated amorphous carbon film in ultra-high vacuum. The as-cooled nanoparticles were studied using bright-field imaging, selected-area diffraction, energy-dispersive X-ray spectroscopy and high-resolution imaging in the transmission electron microscope (TEM). These analyses revealed the presence of two phases in the 20-50 nm diameter nanoparticles: a Ag-rich fcc {alpha}{sub 1} phase and an ordered L1{sub 2} phase (AuCu{sub 3} prototype). The phases were found to have a cube-on-cube (or parallel) orientation relationship with {alpha}{sub 1}-L1{sub 2} interfaces that were parallel to {l_brace}1 0 0{r_brace}. In situ heating of the particles in the TEM showed that the {alpha}{sub 1}-L1{sub 2} {l_brace}1 0 0{r_brace} interface dissolved by steps one moire-fringe spacing high, consistent with recent theories of interface movement. In contrast to previous studies on the stability of ordered phases in Au-Cu alloys, the ordered L1{sub 2} phase in the Ag-Au-Cu alloy remained at temperatures several hundred degrees higher than predicted from the equilibrium bulk phase diagram. This may be caused by elastic stabilization of the phase due to the small size of the particles and/or composition modulations induced by the surface.

• OSTI ID: 20634700
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 10 Vol. 52; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CARBON
COPPER ALLOYS
DIFFRACTION
FCC LATTICES
FILMS
GOLD ALLOYS
HEATING
INTERFACES
NANOSTRUCTURES
PARTICLES
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
PHYSICAL VAPOR DEPOSITION
SILVER ALLOYS
TERNARY ALLOY SYSTEMS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY SPECTROSCOPY