INHOMOGENEITIES IN SINGLE-CRYSTAL COMPONENTS

被引：67

作者：

PAUL, U ^{[1
]}

SAHM, PR ^{[1
]}

GOLDSCHMIDT, D ^{[1
]}

机构：

[1] MOTOREN & TURBINEN UNION MUNCHEN GMBH,D-80995 MUNICH,GERMANY

来源：

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING | 1993年 / 173卷 / 1-2期

关键词：

D O I：

10.1016/0921-5093(93)90185-H

中图分类号：

TB3 [工程材料学];

学科分类号：

0805 ; 080502 ;

摘要：

The temperature distribution during single-crystal solidification of the Ni-based super alloys SRR99 and CMSX-6 by the Bridgman process was measured at various withdrawal rates in dummy turbine blades. Asymmetric heat nux and cross-section transients influence the geometrical formation of the liquidus isotherm and consequently of dendritic growth. The probability of the formation of structural inhomogeneities such as microporosity, zebras, mosaic structures, etc. is largely dependent on the curvature of the solidification front, which in turn depends on the geometrical arrangement of the ceramic cluster and on the withdrawal rate. The proneness to recrystallization during gamma solutioning at cross-section transients due to casting-induced deformation and misaligned dendrites was also examined. Recrystallization remains confined to highly deformed areas as long as microscopic inhomogeneities acting as obstacles are present during heat treatment. High cycle fatigue tests showed that defects such as porosity and local recrystallization reduce the fatigue strength to about half the fatigue strength of the defect-free materials.

引用

页码：49 / 54

页数：6