Pressure-assisted reaction bonding between W and Si sub 80 Ge sub 20 alloy with Ni as the interlayer
- Ames Laboratory and Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011 (US)
The conditions and reaction mechanism of W/Ni/Si{sub 80}Ge{sub 20} hot-press bonding have been studied. It was found that a Ni/Si{sub 80}Ge{sub 20} bond can be formed using low pressure, 19.6 MPa, in the temperature range between 780 and 900 {degree}C in a short time. The kinetics follows a parabolic pattern, suggesting it is a diffusion-controlled process. The activation energy is 2.7 eV and the parabolic rate constant is given by {ital K}{sub {ital P}} = 4.0 {times} 10{sup 14} exp({minus}3.2{times}10{sup 4}/{ital T}) ({mu}m{sup 2}/min). The bonding interface has a multilayered structure. A phenomenological mechanism of the bonding formation has been proposed based on scanning electron microscopy observations and energy dispersive spectroscopy. The cracking problem due to thermal stress is discussed based on Oxx's equation. It was found that bonds free from cracks in the Si{sub 80}Ge{sub 20} alloy are formed when the Ni consumption (as measured by the thickness of the nickel layer) is sufficiently small ({lt}40--45 {mu}m) and the post-hot-press cooling is slow. On the other hand, tungsten and nickel react during hot pressing at higher temperature, forming WNi{sub 4}. As an interlayer, nickel can join the tungsten sheet and the Si{sub 80}Ge{sub 20} together. It has been also demonstrated that a thin nickel layer formed by vapor deposition on a tungsten sheet may be used as the interlayer in place of nickel sheet.
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5744938
- Journal Information:
- Journal of Applied Physics; (USA), Vol. 69:8, Issue 8; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GERMANIUM ALLOYS
BONDING
NICKEL
SILICON ALLOYS
THERMOELECTRIC GENERATORS
TUNGSTEN
ADHESION
AMES LABORATORY
HOT PRESSING
INTERFACES
ALLOYS
DIRECT ENERGY CONVERTERS
ELEMENTS
FABRICATION
JOINING
MATERIALS WORKING
METALS
NATIONAL ORGANIZATIONS
PRESSING
TRANSITION ELEMENTS
US AEC
US DOE
US ERDA
US ORGANIZATIONS
NESDPS Office of Nuclear Energy Space and Defense Power Systems
360101* - Metals & Alloys- Preparation & Fabrication
360601 - Other Materials- Preparation & Manufacture