Oxygen Effects in Ti-TM(V, Cr, Mn, Fe, Co, Ni)-Si Quasicrystals
Abstract
Many reports of icosahedral phase (i-phase) formation in Ti-TM-Si alloys have been published previously. However, oxygen concentration was not quantitatively considered in these earlier studies of samples quenched in a quartz tube. We find that a few atomic percent of oxygen is absorbed from the quartz tube changes the structures obtained from the solid solution to the quasicrystal. Our melt-spun samples were quenched from an out-gassed carbon crucible to investigate the role of silicon and oxygen. Since it is difficult to quantify the local concentration of oxygen in the i-phase, it was assumed to be equal to the amount of oxygen added to the melt. Samples made with more oxygen than the amount required for single i-phase formation contained the α-phase (1/1 approximant). I-phase grains were found in Ti-(Cr,Mn,V,Fe)-Si alloys made with oxygen. These results match predictions using the quantum structural diagram. The minimum amount of oxygen required to form the i-phase, the possible interpretation of the role of oxygen (i.e. thermodynamic or kinetic) and the atomic positions of oxygen in the quasicrystal will be discussed. Results of magnetic measurements with varying oxygen concentration will be presented.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1996
- Bibcode:
- 1996APS..MAR.S1809K