2026-09-20T06:54:37Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/25850 2023-07-10 col_2142_8859 col_2142_5131 com_2142_8858 com_2142_234 com_2142_5130

1970 Lazarus, David Jeffery, Rondo Nelden 2011-07-26T20:20:12Z 2011-07-26T20:20:12Z 10000-01-01 "Diffusion of Ti44 into beta-titanium has been measured as a function of pressure at approximately 10000C using standard lathe-sectioning techniques. The diffusion coefficient is found to decrease with pressure, indicating a positive activation volume. This result is in contradiction of earlier reports of negative activation volumes for diffusion of Fe in S-Ti and U in y-U. The value obtained for the activation volume for self-diffusion in S-Ti is approximately 3.6 ± 1.0 cm3/mOle, corresponding to ~V/VM = 0.33 + 0.1, where VM is the molar volume. Comparison is made with atomic.models and various proposed mechanisms for diffusion in the anomalous body-centered cubic metals. The magnitude of ~V appears to be too large to be consistent with the ""extrinsic"" vacancy mechanism of Kidson, but smaller than would normally be expected for simple vacancy diffusion in bcc metals; It is concluded that diffusion in beta-titanium most probably proceeds via a combination of vacancy and short dislocation-path diffusion, known as the Hart mechanism. Non-gaussian penetration profiles were observed in some of the runs. This has been interpreted in terms of oxide hold-up of the tracer at the surface and possible diffusion of the tracer as an oxide along dislocation pipes or grain boundaries near the surface prior to dissociation." Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-07-26T20:20:12Z No. of bitstreams: 1 1970_jeffery.pdf: 2852702 bytes, checksum: fc1a5fea0d8b1f742fc3ef8f6b61bfdf (MD5) Made available in DSpace on 2011-07-26T20:20:12Z (GMT). No. of bitstreams: 1 1970_jeffery.pdf: 2852702 bytes, checksum: fc1a5fea0d8b1f742fc3ef8f6b61bfdf (MD5) Previous issue date: 1970 Restriction data tranferred 2014-07-01T11:33:10-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-07-26T20:20:12Z Item is restricted indefinitely. Thesis U of I Only 6053442 http://hdl.handle.net/2142/25850 en 1970 Rondo Nelden Jeffery high pressure self-diffusion beta-titanium lathe-sectioning technique The effect of high pressure on self-diffusion in beta-titanium Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.