Title: Structural phase stability in nanocrystalline titanium to 161 GPa

Abstract

Nanocrystalline titanium (nc-Ti) metal was investigated up to 161 GPa at room temperature using a diamond anvil cell. X-ray diffraction and electrical resistance techniques were used to investigate the compressibility and structural phase stability. nc-Ti is observed to undergo three structural phase transitions at high pressures, starting with α → ω at 10GPa and followed by ω → γ at 127GPa and γ → δ at 140GPa. The observed structural phase transitions, as well as compressibility, are consistent with previously reported values for coarse grained Ti (c-Ti). The high pressure experiments on nc-Ti samples do no show any significant variation of the α → ω transition pressure under varying nonhydrostatic conditions. This is in sharp contrast to c-Ti, where a significant decrease in the α → ω transition pressure is observed under increasing nonhydrostatic conditions. As a result, this would indicate that the decrease in grain size in nano grained titanium makes the α → ω phase transition less sensitive to shear stresses as compared to bulk or c-Ti.

Authors:

Velisavljevic, Nenad; Jacobsen, Matthew K.; Vohra, Yogesh K.

Publication Date:

Mon Sep 01 00:00:00 EDT 2014

Research Org.:

Univ. of Alabama, Birmingham, AL (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1342435

Alternate Identifier(s):

OSTI ID: 1251166

Grant/Contract Number:  

AC52-06NA25396; NA0002014

Resource Type:

Published Article

Journal Name:

Materials Research Express (Online)

Additional Journal Information:

Journal Name: Materials Research Express (Online) Journal Volume: 1 Journal Issue: 3; Journal ID: ISSN 2053-1591

Publisher:

IOP Publishing

Country of Publication:

United Kingdom

Language:

English

Subject:

36 MATERIALS SCIENCE; high pressure; diamond anvil cell; titanium; electrical resistance