A model of convection-induced oscillatory structure formation in peritectic alloys

Journal Article · Sat Apr 01 04:00:00 EST 2000 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-000-0119-x· OSTI ID:20050554

Mazumder, P; Trivedi, R; Karma, A

In the two-phase region of a peritectic system, experimental studies have shown that the primary phase ({alpha}) often forms a large treelike structure that is surrounded by the peritectic phase ({beta}). The formation of this novel structure has been attributed to the presence of convection in the liquid. Here, specific physical mechanisms of convection-induced treelike structure formation are proposed. A mathematical model based on advection-diffusion of solute, with prototype flows for advection, is presented and solved numerically to show that an oscillating fluid motion can give rise to a complex oscillatory, treelike structure. Three different regimes are established: diffusive, steady convective, and unsteady convective regimes. In the diffusive regime, a banded structure is predicted within a narrow composition range, and the spacing of the bands is dictated by the nucleation undercoolings of the two phases. Under steady convection, the primary phase transforms into the peritectic phase with a curved {alpha}:{beta} interface. Finally, in the presence of oscillating convection, a treelike shape of the primary phase is predicted, as observed experimentally.

• Research Organization: Corning Inc., NY (US)
• Sponsoring Organization: National Aeronautics and Space Administration; US Department of Energy
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 20050554
• 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: 4 Vol. 31; ISSN MMTAEB; ISSN 1073-5623
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALLOYS
CONVECTION
DIFFUSION
INTERFACES
LIQUID METALS
MATHEMATICAL MODELS
MICROSTRUCTURE
PHASE DIAGRAMS