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Title: In-situ Studies of the Martensitic Transformation in Ti Thin Films using the Dynamic Transmission Microscope (DTEM)

Abstract

The {alpha} to {beta} transition in pure Ti occurs mainly by a 'martensitic type' phase transformation. In such transformations, growth rates and interface velocities tend to be very large, on the order of 10{sup 3} m/s, making it difficult to observe the transformation experimentally. With thin films, it becomes even more difficult to observe, since the large surface augments the nucleation and transformation rates to levels that require nanosecond temporal resolution for experimental observations. The elucidation of the transformational mechanisms in these materials yearns for an apparatus that has both high spatial and temporal resolution. We have constructed such an instrument at LLNL (the dynamical transmission electron microscope or DTEM) that combines pulsed lasers systems and optical pump-probe techniques with a conventional TEM. We have used the DTEM to observe the transient events of the {alpha}-{beta} transformation in nanocrystalline Ti films via single shot diffraction patterns with 1.5 ns resolution. With pulsed, nanosecond laser irradiation (pump laser), the films were heated at an extreme rate of 10{sup 10} K/s. was observed At 500 ns after the initial pump laser hit, the HCP, alpha phase was almost completely transformed to the BCC, beta phase. Post-mortem investigations of the laser treated filmsmore » revealed that substantial grain growth occurred and lath microstructure, containing no apparent dislocations. The lack of dislocations may indicate that the {alpha} to {beta} transformation may also proceed by a 'massive' type mechanism (short range diffusion).« less

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
928203
Report Number(s):
UCRL-PROC-217255
TRN: US200815%%778
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: Materials Research Society Fall Meeting 2005, Boston, MA, United States, Nov 28 - Dec 02, 2005
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; DIFFRACTION; DIFFUSION; DISLOCATIONS; ELECTRON MICROSCOPES; GRAIN GROWTH; IRRADIATION; LASERS; LAWRENCE LIVERMORE NATIONAL LABORATORY; MICROSCOPES; MICROSTRUCTURE; NUCLEATION; PHASE TRANSFORMATIONS; RESOLUTION; THIN FILMS; TRANSFORMATIONS; TRANSIENTS

Citation Formats

LaGrange, T B, Campbell, G H, Colvin, J D, King, W E, Browning, N D, Armstrong, M R, Reed, B W, Kim, J S, and Stuart, B C. In-situ Studies of the Martensitic Transformation in Ti Thin Films using the Dynamic Transmission Microscope (DTEM). United States: N. p., 2005. Web.
LaGrange, T B, Campbell, G H, Colvin, J D, King, W E, Browning, N D, Armstrong, M R, Reed, B W, Kim, J S, & Stuart, B C. In-situ Studies of the Martensitic Transformation in Ti Thin Films using the Dynamic Transmission Microscope (DTEM). United States.
LaGrange, T B, Campbell, G H, Colvin, J D, King, W E, Browning, N D, Armstrong, M R, Reed, B W, Kim, J S, and Stuart, B C. Mon . "In-situ Studies of the Martensitic Transformation in Ti Thin Films using the Dynamic Transmission Microscope (DTEM)". United States. doi:. https://www.osti.gov/servlets/purl/928203.
@article{osti_928203,
title = {In-situ Studies of the Martensitic Transformation in Ti Thin Films using the Dynamic Transmission Microscope (DTEM)},
author = {LaGrange, T B and Campbell, G H and Colvin, J D and King, W E and Browning, N D and Armstrong, M R and Reed, B W and Kim, J S and Stuart, B C},
abstractNote = {The {alpha} to {beta} transition in pure Ti occurs mainly by a 'martensitic type' phase transformation. In such transformations, growth rates and interface velocities tend to be very large, on the order of 10{sup 3} m/s, making it difficult to observe the transformation experimentally. With thin films, it becomes even more difficult to observe, since the large surface augments the nucleation and transformation rates to levels that require nanosecond temporal resolution for experimental observations. The elucidation of the transformational mechanisms in these materials yearns for an apparatus that has both high spatial and temporal resolution. We have constructed such an instrument at LLNL (the dynamical transmission electron microscope or DTEM) that combines pulsed lasers systems and optical pump-probe techniques with a conventional TEM. We have used the DTEM to observe the transient events of the {alpha}-{beta} transformation in nanocrystalline Ti films via single shot diffraction patterns with 1.5 ns resolution. With pulsed, nanosecond laser irradiation (pump laser), the films were heated at an extreme rate of 10{sup 10} K/s. was observed At 500 ns after the initial pump laser hit, the HCP, alpha phase was almost completely transformed to the BCC, beta phase. Post-mortem investigations of the laser treated films revealed that substantial grain growth occurred and lath microstructure, containing no apparent dislocations. The lack of dislocations may indicate that the {alpha} to {beta} transformation may also proceed by a 'massive' type mechanism (short range diffusion).},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Nov 21 00:00:00 EST 2005},
month = {Mon Nov 21 00:00:00 EST 2005}
}

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