25Mg NMR site analysis in metals and intermetallics.
Nuclear magnetic resonance (NMR) of the low abundance and low gyromagnetic ratio isotope (25)Mg, I=5/2, 2.606MHz/T, 10% abundant, is shown here to provide an informative probe for phase identification, site symmetry and site multiplicity of the intermetallic compounds which occur as strengthening precipitate phases in lightweight alloys. The intermetallics discussed here, Mg(17)Al(12), MgZn(2), Mg(2)Al(3) and Al(2)CuMg, are the final equilibrium precipitate phases in a number of Mg- and Al-based heat-treatable alloys. The (25)Mg spectra of Mg in Al-10at%Mg alloy show the progressive precipitation of Mg(2)Al(3) from Mg in solid solution as a function of annealing time at 150 degrees C. Also reported are (25)Mg spectra for CuMg(2), Mg(44)Al(15)Zn(41) and Mg(2)Sn, along with the counter atom (67)Zn and (63)Cu NMR spectra for MgZn(2) and CuMg(2). All spectra are simulated to determine nuclear interaction parameters and confirm site occupancy.
Bastow
T J
TJ
CSIRO Materials Science and Engineering, Clayton, Vic, Australia. Tim.Bastow@csiro.au
Celotto
S
S