G. Subhash et al., PLASTIC-DEFORMATION OF HAFNIUM UNDER UNIAXIAL COMPRESSION, Metallurgical and materials transactions. A, Physical metallurgy andmaterials science, 28(7), 1997, pp. 1479-1487
The plastic behavior of polycrystalline hafnium (Hf) was investigated
over a range of sh-ain rates under uniaxial compression. Hafnium exhib
ited considerable ductility and a moderately rate-sensitive plastic be
havior. The stress-strain response consisted of initial yielding follo
wed by parabolic hardening. Microstructural observations on quasistati
cally deformed specimens revealed that yielding occurred by dislocatio
n activity and that hardening was dominated by twinning on {<10(1)over
bar2>} planes and by slip/twin interactions. A considerable reduction
in dislocation and twinning activity was observed in specimens deform
ed at high strain rates. Failure occurred by shear localization and vo
id growth and coalescence within the shear bands. Measurement of the t
emperature rise during high strain rate deformation was also made. Fro
m these measurements, the fraction of work converted to heat as a func
tion of strain was determined and found to decrease with increasing st
rain.