A. Takahashi et al., MICRO-ALLOYED HIGH-PURITY ALUMINUM FOR LOW-TEMPERATURE CONDUCTOR APPLICATIONS, Physica status solidi. a, Applied research, 160(2), 1997, pp. 413-418
The development of micro-alloyed high-purity aluminum for low-temperat
ure superconductor stabilizer applications is described. The base alum
inum is 99.9998% pure; the micro-alloy levels range from 5 up to 90 wt
ppm. Individual elements are added to the base in binary form; the so
lute elements used are B, Ca, Ce, Ga or Y. The effects of solute eleme
nts and solute concentration on electrical, mechanical, and crystallog
raphic properties and on cyclic-strain resistivity degradation at 4.2
K are presented. The addition of low levels of various elements change
s these properties with minimal effects on resistivity, and alloyed ma
terials exhibit lower levels of cyclic-strain resistivity degradation
than the base high-purity aluminum. Our results show that this improve
ment in resistivity degradation is closely related to grain refinement
resulting from the addition of solute elements and sample preparation
procedures. Optical micrographs show the presence of particles that o
ccurred as a result of micro-segregation during the initial solidifica
tion.