The effects of Ti and Mo additions on the microstructure of Nb-silicide based in situ composites

被引：94

作者：

Geng, J. ^{[1
]}

Tsakiropoulos, P. ^{[1
]}

Shao, G. ^{[1
]}

机构：

[1] Univ Surrey, Sch Engn, Met Res Grp, Guildford GU2 7XH, Surrey, England

来源：

INTERMETALLICS | 2006年 / 14卷 / 03期

关键词：

silicides; various; laves phases; phase diagrams; phase transformations; electron microscopy; scanning;

D O I：

10.1016/j.intermet.2005.04.021

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 effects of Ti and Mo additions on phase selection, phase transformations and microstructure development in as cast and heat-treated Nb-Si-Cr-Al in situ composites have been investigated. The beta Nb5Si3 was formed in all the as cast alloys, which are classified as hypereutectic alloys. After heat treatment at 1500 degrees C, the beta Nb5Si3 transformed to alpha Nb5Si3 completely or partially. The lattice parameter of the bee Nb solid solution (Nb-ss) decreased with the addition of Ti and with increasing Mo concentration. The C14-Cr2Nb Laves phase was absent in the alloys with Ti addition at 24at.% in the presence of Mo (<= 5 at.%). The eutectoid decomposition of Nb3Si to Nb-ss and alpha Nb5Si3 was very sluggish in the alloy without Ti but it was enhanced with the addition of Ti. The partitioning of Ti between the Nb-ss and (Nb,Ti)(5)Si-3 led to the formation of Ti-rich (Nb,Ti)(5)Si-3, where the concentration of Ti was about 30.3 at.% in the heat treated microstructure. Nb, particles precipitated inside aNb(5)Si(3) in the heat treated alloys. (c) 2005 Elsevier Ltd. All rights reserved.

引用

页码：227 / 235

页数：9

共 22 条

[1]

Balsone SJ, 2001, STRUCTURAL INTERMETALLICS 2001, P99

[2] The Nb-Ti-Si ternary phase diagram: Evaluation of liquid-solid phase equilibria in Nb- and Ti-rich alloys [J].

Bewlay, BP ;

Jackson, MR ;

Lipsitt, HA .

JOURNAL OF PHASE EQUILIBRIA, 1997, 18 (03) :264-278

[3] The balance of mechanical and environmental properties of a multielement niobium-niobium silicide-based in situ composite [J].

Bewlay, BP ;

Jackson, MR ;

Lipsitt, HA .

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, 1996, 27 (12) :3801-3808

[4]

BEWLAY BP, 2000, INTERMETALLIC COMPOU, V3, P541

[5]

BEWLAY BP, 2001, MRS S P, V646

[6] Improving the fracture toughness of constituent phases and Nb-based in-situ composites by a computational alloy design approach [J].

Chan, KS ;

Davidson, DL .

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, 2003, 34A (09) :1833-1849

[7] Alloying effects on fracture mechanisms in Nb-based intermetallic in-situ composites [J].

Chan, KS .

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 2002, 329 :513-522

[8] Effects of Ti addition on cleavage fracture in Nb-Cr-Ti solid-solution alloys [J].

Chan, KS ;

Davidson, DL .

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, 1999, 30 (04) :925-939

[9]

Cullity BD, 1978, ELEMENTS XRAY DIFFRA

[10] THE CONSTITUTION OF THE CHROMIUM NIOBIUM SILICON SYSTEM [J].

GOLDSCHMIDT, HJ ;

BRAND, JA .

JOURNAL OF THE LESS-COMMON METALS, 1961, 3 (01) :34-43

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