dc.contributor.advisor Barrera, Enrique V. Chen, Jinmin 2009-06-04T06:29:47Z 2009-06-04T06:29:47Z 1997 https://hdl.handle.net/1911/17070 In an effort to expand the composition range over which Al$\sb3$Ti is stable, various amounts of niobium were substituted for titanium and processed by melt-spinning. In order to characterize $\rm Al\sb3Ti\sb{x}Nb\sb{y},$ where x + y = 1 and y = 0.0, 0.1, 0.2, and 0.4 intermetallics, XRD and EXAFS were employed. Several samples were annealed both at 600$\sp\circ$C and 1000$\sp\circ$C. XRD showed that for all the samples the only structure present was the tetragonal DO$\sb{22}$ structure. The DO$\sb{22}$ structure was stable even after high temperatures heat treatments. Niobium atoms were observed to occupy titanium sites in DO$\sb{22}$ by EXAFS. Furthermore, in the unannealed samples, increasing wheel speed of the melt spinning process or the niobium concentration tended to distort the crystal structure. It was observed that Ti EXAFS had different results from the Nb EXAFS beyond their occupying similar sites. The samples were found to experience an order-disorder-order process with change of the annealing temperatures. 76 p. application/pdf eng Condensed matter physicsEngineeringMaterials science A structural analysis of Al(3)Ti and Al(3)Ti-Nb titanium trialuminides by XRD and EXAFS Thesis Text Physics Natural Sciences Rice University Masters Master of Science Chen, Jinmin. "A structural analysis of Al(3)Ti and Al(3)Ti-Nb titanium trialuminides by XRD and EXAFS." (1997) Master’s Thesis, Rice University. https://hdl.handle.net/1911/17070.
﻿