Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Phase Transformations and Formation of Ultra-Fine Microstructure During Hydrogen Sintering and Phase Transformation (HSPT) Processing of Ti-6Al-4V

Journal Article · · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

The hydrogen sintering and phase transformation (HSPT) process is a novel powder metallurgy method for producing Ti alloys, particularly the Ti-6Al-4V alloy, with ultra-fine microstructure in the as-sintered state. The ultra-fine microstructure is obtained as a direct result of the use of H-2 gas during sintering. The refinement of the microstructure during HSPT is similar to that of thermal hydrogen processing (THP) of bulk Ti alloys. For both THP and HSPT of Ti-6Al-4V alloy, the mechanisms of the grain refinement depend on the phase equilibria and phase transformations in the presence of hydrogen, which are surprisingly still not well established to date and are still subjected to research and debate. In recent work by the present authors, a pseudo-binary phase diagram of (Ti-6Al-4V)-H has been determined by using in situ synchrotron XRD and TGA/DSC techniques. Aided by this phase diagram, the current paper focuses on the series of phase transformations during sintering and cooling of Ti-6Al-4V in a hydrogen atmosphere and the mechanisms for the formation of the ultra-fine microstructures obtained. Using experimental techniques, including in situ synchrotron XRD, SEM, EBSD, and TEM, the microstructural refinement was found to be the result of (1) the precipitation of ultra-fine alpha/alpha(2) within coarse beta grains during an isothermal hold at intermediate temperatures, and (2) the eutectoid transformation of beta -> alpha + delta d at approximately 473 K (200 degrees C). (C) The Minerals, Metals & Materials Society and ASM International 2015

Research Organization:
Argonne National Laboratory (ANL)
Sponsoring Organization:
Argonne National Laboratory - Advanced Photon Source
DOE Contract Number:
AC02-06CH11357
OSTI ID:
1391995
Journal Information:
Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 12 Vol. 46; ISSN 1073-5623
Publisher:
ASM International
Country of Publication:
United States
Language:
English

References (23)

Pathways to Optimize Performance/Cost Ratio of Powder Metallurgy Titanium – A Perspective journal August 2012
Titanium book January 2003
A transmission electron microscopy and three-dimensional atom probe study of the oxygen-induced fine microstructural features in as-sintered Ti–6Al–4V and their impacts on ductility journal April 2014
Titanium and Titanium Alloys: Fundamentals and Applications book July 2003
Novel fabrication of titanium by pure microwave radiation of titanium hydride powder journal July 2013
Phase transformations in Ti-6Al-4V-xH alloys journal October 2001
An experimental study of the (Ti–6Al–4V)–xH phase diagram using in situ synchrotron XRD and TGA/DSC techniques journal February 2015
Influence of processing on microstructure and mechanical properties of (α+β) titanium alloys journal March 1998
Synthesis of Alloy Ti ― 6Al ― 4V with Low Residual Porosity by a Powder Metallurgy Method journal January 2002
A coupled EBSD/EDS method to determine the primary- and secondary-alpha textures in titanium alloys with duplex microstructures journal October 2008
Nano-twin mediated plasticity in carbon-containing FeNiCoCrMn high entropy alloys journal October 2015
A powder metallurgy method for manufacturing Ti-6Al-4V with wrought-like microstructures and mechanical properties via hydrogen sintering and phase transformation (HSPT) journal October 2015
Hydrogen Sintering of Titanium to Produce High Density Fine Grain Titanium Alloys journal April 2012
Fatigue Resistance of Powder Metallurgy Ti–6Al–4V Alloy journal May 2004
Characterization of the α Phase Nucleation in a Two-Phase Metastable β Titanium Alloy journal December 2005
Thermodynamic evaluation of the titanium-hydrogen system journal May 1996
Hydrogen as a temporary alloying element in titanium alloys: thermohydrogen processing journal June 2004
Automatic analysis of electron backscatter diffraction patterns journal March 1992
Microstructures and mechanical properties of compositionally complex Co-free FeNiMnCr18 FCC solid solution alloy journal July 2015
In Situ Synchrotron Radiation Study of TiH2-6Al-4V and Ti-6Al-4V: Accelerated Alloying and Phase Transformation, and Formation of an Oxygen-Enriched Ti4Fe2O Phase in TiH2-6Al-4V journal October 2014
Mechanical property optimization via microstructural control of new metastable beta titanium alloys journal January 2007
The effect of hydrogen as a temporary alloying element on the microstructure and tensile properties of Ti-6Al-4V journal June 1985
The Beta Titanium Alloys journal July 1985

Similar Records

An experimental study of the (Ti-6Al-4V)-xH phase diagram using in situ synchrotron XRD and TGA/DSC techniques.
Journal Article · Sat Jan 31 23:00:00 EST 2015 · Acta Materialia · OSTI ID:1239625

Analysis of microstructural facet fatigue failure in ultra-fine grained powder metallurgy Ti-6Al-4V produced through hydrogen sintering
Journal Article · Mon Oct 28 00:00:00 EDT 2019 · International Journal of Fatigue · OSTI ID:1799184

Lattice variations of Ti-6Al-4V alloy with hydrogen content
Journal Article · Fri Jul 15 00:00:00 EDT 2011 · Materials Characterization · OSTI ID:22066371

Related Subjects