Fundamental studies on microstructural evolution of two-phase titanium alloys

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:6174986

Grewal, G S

A systematic study was undertaken to determine the affect of temperature and diffusivity of alloying elements on the particle coarsening and grain growth kinetics of various two phase materials using Ti-Mn and Ti-V alloys as the model systems. During the course of this investigation, it was found that the titanium end of the Ti-V phase diagram is incorrect. Based on the results of this investigation, a new phase diagram was proposed. A model was proposed for two phase materials where solute and solvent atoms move in opposite directions resulting in coarsening of particles. In addition to this bulk diffusion mechanism, additional mechanisms were considered. It is found that mixed diffusion (grain boundary + lattice) controls the coarsening of particles at 973 K for the Ti-Mn system whereas predominantly grain boundary diffusion is the controlling mechanism for the Ti-V system at 973 K. Studies on the effect of temperature on particle coarsening showed that the activation energy for particle coarsening process increases with an increase in temperature. In addition, it is found that the coarsening exponents also increase with increase in temperature. It is proposed that the particle coarsening mechanism changes from mixed diffusion control towards bulk diffusion control as the temperature increases from 973 to 1108 K for the Ti-Mn system. It is also suggested that the coarsening mechanism changes from predominantly grain boundary diffusion control to mixed diffusion control as the temperature is increased from 973 to 1073 K for the Ti-V system. The growth of matrix grains in the presence of growing second phase particles was also studied. A model based on classical driving force for grain growth and a modified form of Zener retardation is proposed for the growth of matrix grains.

• Research Organization: Maryland Univ., College Park, MD (USA)
• OSTI ID: 6174986
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ACTIVATION ENERGY
ALLOYS
CRYSTAL STRUCTURE
DATA
ENERGY
EXPERIMENTAL DATA
GRAIN BOUNDARIES
INFORMATION
MANGANESE ALLOYS
MICROSTRUCTURE
NUMERICAL DATA
TEMPERATURE EFFECTS
TITANIUM ALLOYS
VANADIUM ALLOYS