Paper Title:
Residual Stresses and Void Kinetics in AlSiC MMCs during Thermal Cycling
  Abstract

AlSi7Mg/SiC/70p (AlSiC) is used for heat sinks because of its good thermal conductivity combined with a low coefficient of thermal expansion (CTE). These properties are important for power electronic devices where heat sinks have to provide efficient heat transfer to a cooling device. A low CTE is essential for a good surface bonding of the heat sink material to the insulating ceramics. Otherwise mismatch in thermal expansion would lead to damage of the bonding degrading the thermal contact within the electronic package. Therefore AlSiC replaces increasingly copper heat sinks. The CTE mismatch between insulation and a conventional metallic heat sink is transferred into the MMC heat sink. The stability of the interface bonding within a MMC is critical for its thermal properties. In situ thermal cycling measurements of an AlSi7Mg/SiC/70p MMC are reported yielding the void volume fraction and internal stresses between the matrix and the reinforcements in function of temperature. The changes in void volume fractions are determined simultaneously by synchrotron tomography and residual stresses by synchrotron diffraction at ESRF-ID-15. The measurements show a relationship between thermal expansion, residual stresses and void formation in the MMC. The results obtained from the in situ measurements reveal a thermoelastic range up to 200 °C followed by plastic matrix deformation reducing the volume of voids during heating. A reverse process takes place during cooling. Thus the CTE becomes smaller than according to thermoelastic calculations. Damage could be observed after multiple heating cycles, which increase the volume fraction and the size of the voids. The consequence is local debonding of the matrix from the reinforcement particles, which leads to an irreversible reduction of the thermal conductivity after multiple heating cycles.

  Info
Periodical
Materials Science Forum (Volumes 571-572)
Edited by
A. R. Pyzalla, A. Borbély and H.-P. Degischer
Pages
413-418
DOI
10.4028/www.scientific.net/MSF.571-572.413
Citation
M. Schöbel, G. C. Requena, H. Kaminski, H. P. Degischer, T. Buslaps, M. Di Michiel, "Residual Stresses and Void Kinetics in AlSiC MMCs during Thermal Cycling", Materials Science Forum, Vols. 571-572, pp. 413-418, 2008
Online since
March 2008
Export
Price
$32.00
Share

In order to see related information, you need to Login.

In order to see related information, you need to Login.

Authors: Zhi Ying Ou, Dong Xia Lei, Lian Sheng Ma
Abstract:The residual stresses induced in fiber-reinforced functionally graded composites cooling down from the processing temperature are determined...
1044
Authors: Xian Liang Zhou, Duo Sheng Li, Ai Hua Zou, Xiao Zhen Hua, Zhi Guo Ye, Qing Jun Chen
New Functional Materials
Abstract:SiCp/Al composites were fabricated by ceramic mold freedom infiltration and pressureless infiltration, respectively. The microstructure and...
658
Authors: Chao Sun, Rujuan Shen, Min Song, Yong Du
Chapter 1: Composites
Abstract:The effects of SiC particle size, volume fraction and tensile strain on the deformation behaviors of SiC particle reinforced Al matrix...
3
Authors: Dong Chen, Zhe Chen, Peng Zhang, Yi Jie Zhang, Haiheng Ma, Hao Wei Wang
Chapter 5: Metal Alloy Materials
Abstract:In-situ TiB2 particles reinforced AA7055 composites were fabricated through mixed-salts route and their bending properties were...
1005
Authors: Ai Hua Zou, Xian Liang Zhou, Duo Sheng Li, Xiao Zhen Hua
Chapter 1: Materials Engineering. Technologies and Processing
Abstract:In this paper, based on the parameters of cumulative residual strain(CRS), the effects of different contents of Mg and Si elements in Al...
335