TY - JOUR
T1 - Kirkendall void formation during room-temperature air-oxidation of thin aluminium and aluminium-lithium alloy films
AU - Tanner, David A.
AU - Belochapkine, Serguei
AU - Laffir, Fathima
AU - Nakahara, Shohei
PY - 2012/8
Y1 - 2012/8
N2 - The effect of room-temperature (~20°C) air-oxidation on void formation in sputter-deposited thin films of aluminum and its alloys was investigated using a transmission electron microscope. It was found that after air-oxidation, only lithium-bearing aluminum alloy films exhibited a high (~4×10 16 cm-3) density of small (~2 nm) voids, whereas pure aluminum or lithium-free aluminum alloy films did not contain any voids. In lithium-bearing aluminum alloy films, both aluminum and lithium atoms migrate to the surfaces to form their surface oxide during room-temperature ageing after film deposition. In the course of the atom migration, excess vacancies are generated as a result of the large diffusivity difference existing between aluminum and lithium atoms (DLi in Al≫DAl) in the alloy matrix. The agglomeration of these excess vacancies led to the formation of so-called Kirkendall voids inside the alloy. Thus the presence of both aluminum and lithium in the alloys was a key factor for generating these Kirkendall voids in the films.
AB - The effect of room-temperature (~20°C) air-oxidation on void formation in sputter-deposited thin films of aluminum and its alloys was investigated using a transmission electron microscope. It was found that after air-oxidation, only lithium-bearing aluminum alloy films exhibited a high (~4×10 16 cm-3) density of small (~2 nm) voids, whereas pure aluminum or lithium-free aluminum alloy films did not contain any voids. In lithium-bearing aluminum alloy films, both aluminum and lithium atoms migrate to the surfaces to form their surface oxide during room-temperature ageing after film deposition. In the course of the atom migration, excess vacancies are generated as a result of the large diffusivity difference existing between aluminum and lithium atoms (DLi in Al≫DAl) in the alloy matrix. The agglomeration of these excess vacancies led to the formation of so-called Kirkendall voids inside the alloy. Thus the presence of both aluminum and lithium in the alloys was a key factor for generating these Kirkendall voids in the films.
KW - Aluminum- lithium alloyz
KW - Kirkendall void
KW - Transmission electron microscopy
KW - X-ray photo-electron spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=84872703749&partnerID=8YFLogxK
U2 - 10.3184/174751912X13348570381901
DO - 10.3184/174751912X13348570381901
M3 - Article
AN - SCOPUS:84872703749
SN - 0960-3409
VL - 29
SP - 235
EP - 242
JO - Materials at High Temperatures
JF - Materials at High Temperatures
IS - 3
ER -