您目前的位置: 首页» 新闻动态

"DIRECTIONAL RECRYSTALLIZATION PROCESSING"学术报告

 

国家重点实验室学术讲座

SKL-AMM Seminar

 

题目/TitleDIRECTIONAL RECRYSTALLIZATION PROCESSING

报告人/SpeakerI. Baker

报告人工作单位/AffiliationThayer School of Engineering

Dartmouth College, Hanover, NH 03755, U.S.A.

 

日期/Date2010915 周三   September 15 , 2010 Wednesday

时间/Time10:00 ? 11:00 AM

联系人/Contact叶丰 教授, Prof. Ye Feng

报告地点/Location:北京科技大学主楼 353,  353 Main Building, USTB

 

Ian Baker

 

 

Senior Associate Dean for Academic Affairs, Thayer School of Engineering, Dartmouth College, and also External Faculty member, Graduate Faculty, U. Maine-Orono, ME. He got his Ph D at Metallurgy and Science of Materials, University of Oxford, England in 1982. He is in Editorial Board of International Materials Reviews (2002-), Editorial Advisory Board of Intermetallics (1998-), and Editorial Advisory Board of Materials Characterization (2002-2003). His research interests include: Mechanical behavior, including wear and fracture of metals, compound semiconductors, intermetallic compounds and ice; processing and intermetallic compounds; recrystallization phenomena, particularly the effect of particles on recrystallization and processing by directional recrystallization; interdiffusion phenomena in metallic thin films and their influence on mechanical properties; applications of electron microscopy, X-ray diffraction and X - ray topography, particularly in-situ deformation experiments; the structure, chemistry and properties of fir and ice cores; production and properties of nanocrystalline, particularly magnetic, materials; nanoparticles for biomedical applications.

 

 

Abstract

 

The microstructures of both isothermally-annealed and directionally-recrystallized cold-rolled polycrystalline nickel have been investigated using both EBSPs on a SEM and optical microscopy.  Isothermally annealed nickel showed a {100}<001> texture and small grains after primary recrystallization at low temperature (700K), but a {124}<21 > texture and large grains after secondary recrystallization at higher temperatures (1000K).  The effects of hot zone velocity, hot zone temperature and temperature gradient ahead of the hot zone on the microstructure produced by directional annealing will be outlined.  Columnar grains could be produced over a wide range of hot zone velocities, but only at high temperature (1100K) with a large temperature gradient.  Experiments on cold-rolled specimens isothermally annealed at 643K prior to directional recrystallization at 1273K showed that directional recrystallization to columnar grains or, under optimum conditions, a single crystal was always by secondary recrystallization, and that a key requirement was texture pinning of the primary recrystallized microstructure.  Results of simulations of directional recystallization using a front-tracking model will also be presented for both particle-free and particle-containing material, and compared to experimental observations on both nickel and the nickel-based superalloy MA 754.