Influence of Grain Boundaries on High Temperature Strength of Polycrystalline Solids
Abstract
Grain boundaries may influence high temperature strength in many ways: as barriers to disloca tion motion, as sources or sinks of vacancies and dislocations, and by grain boundary shearing. In all of these considerations the type of boundary must be taken into account. Experimental results on the influence of grain size on creep of alu minum suggest why coarse grain materials are often stronger in their steady state creep resist ance over fine grain materials. As-recrystallized fine grain aluminum is weak because it usually contains high angle random boundaries and as such can easily deform by boundary shearing; in addi tion, such boundaries may be good sources or sinks of dislocations and vacancies. On the other hand, coarse grain aluminum is strong because it devel ops subgrains during creep; the subgrain bound aries, which consist of dislocations, are good barriers to dislocations, and these boundaries do not exhibit shearing. The strength of the sub grain boundary formed during creep of coarse grain aluminum appears to be strongly dependent on purity; addition of 250 atom parts per million iron increases the steady state creep resistance of coarse grain aluminum by one thousand times at 400 deg C.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 15, 1963
- Accession Number
- AD0410520
Entities
People
- Herbert J. Busboom
- Jack L. Lytton
- Oleg D. Sherby
Organizations
- Stanford University