Metastable phase formation in undercooled eutectic Ni78.6Si21.4 melts

被引：36

作者：

Leonhardt, H ^{[1
]}

Löser, W ^{[1
]}

Lindenkreuz, HG ^{[1
]}

机构：

[1] Inst Festkorper & Werkstofforsch Dresden, D-01171 Dresden, Germany

来源：

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING | 1999年 / 271卷 / 1-2期

关键词：

nickel alloy; eutectic melts; melt undercooling; metastable phase formation;

D O I：

10.1016/S0921-5093(99)00161-6

中图分类号：

TB3 [工程材料学];

学科分类号：

0805 ; 080502 ;

摘要：

Non-equilibrium solidification processes in bulk undercooled eutectic Ni78.6Si21.4 melts are investigated with respect to metastable phase and microstructure formation. Melt undercooling levels up to 250 K have been achieved by an electromagnetic levitation technique. The in-situ observation of recalescence events was accomplished by a fast responding silicon diode. Levitated drops of controlled undercooling prior to solidification were quenched onto chill substrates. A transition from coupled eutectic to primary dendrite growth beyond a critical undercooling level of 30-50 K was revealed from double-recalescence events. Quenched samples displayed a featureless zone of the metastable hexagonal high-temperature phase Ni25Si9, which replaces the equilibrium phases. The metastable dendrites gradually decompose into an anomalous eutectic microstructure on slow post-solidification cooling. (C) 1999 Elsevier Science S.A. All rights reserved.

引用

页码：31 / 37

页数：7

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