Grain refinement by low boron additions in niobium-rich TiAl-based alloys

被引：212

作者：

Hecht, U. ^{[1
]}

Witusiewicz, V. ^{[1
]}

Drevermann, A. ^{[1
]}

Zollinger, J. ^{[1
]}

机构：

[1] ACCESS Mat & Proc, D-52072 Aachen, Germany

来源：

INTERMETALLICS | 2008年 / 16卷 / 08期

关键词：

titanium aluminides; based on TiAl; phase transformations; casting; microstructure; diffraction;

D O I：

10.1016/j.intermet.2008.04.019

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The grain refinement achieved with low boron additions to selected TiAl-based alloys was investigated in unidirectional solidified samples by means of EBSD-orientation mapping of the alpha(Ti) phase, retained by quenching. The analysis shows that excellent grain refinement is achieved during the solid state transformation of the body centred beta(Ti) into the hexagonal close packed alpha(Ti). It leads to a fairly random orientation of the alpha(Ti) grains which indicates that heterogeneous nucleation of alpha(Ti) on borides is at the origin of refinement. The borides were identified to be orthorhombic (Ti,Nb)B monoboride ribbons with the crystal structure of NbB. The refinement is severely impeded by peritectic growth of alpha(Ti): peritectic alpha(Ti) grains almost completely invade the microstructure by imposing their crystal orientation through all subsequent solid state transformations. (C) 2008 Elsevier Ltd. All rights reserved.

引用

页码：969 / 978

页数：10

共 17 条

[1]

Appel F, 2003, GAMMA TITANIUM ALUMINIDES 2003, P139

[2]

Blackburn MJ, 1970, SCI TECHNOLOGY APPL, P633

[3] On the process of transition of the cubic-body-centered modification into the hexagonal-close-packed modification of zirconium [J].