Abstract
The objective of this research is to investigate the effects of orientation on strain hardening and resistivity degradation in high purity aluminum single crystals resulting from uniaxial cyclic strain at 4.2 K. Aluminum crystals with various orientations were grown by the Chalmers technique; pure and micro-alloyed < 100 > and < 111 > orientations were prepared by a casting method. All of the specimens were cyclic strained at +-0.1 % strain amplitude through at least 500 cycles. Changes in maximum stress and residual resistivity during the cycling are reported and the effects of orientation on properties are discussed. It is found that a high resistivity increase rate and a high work hardening rate at the beginning of cyclic deformation results in the least amount of resistivity increase at saturation. Crystals with < 100 > and < 111 > aligned along the stress axis are found to exhibit significantly higher rates of strain hardening and dramatically lower levels of cyclic strain resistivity degradation than crystals oriented differently. Deviations of greater than six degrees from the [111] and [100] poles result in significantly weakened crystals which show high resistivity degradation. The addition of 22 ppm cerium to cast < 100 > and < 111 > crystals has little effect on strain hardening and resistivity degradation behavior.
Zou, Hong (1995). Electrical and mechanical studies of high purity aluminum single crystals at 4.2 K under cyclic strain. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1995 -THESIS -Z65.