Superplastic Deformation of the Zn-Al Eutectoid at Constant Strain Rates.

摘要

Tensile samples of three different grain sizes were prepared from the Zn-Al eutectoid and deformed at 250C at constant strain rates from .0004/min to .11/min in a modified Instron testing machine. Strain hardening was observed at low strain rates for the 0.5and the 0.9micrometer grain size samples and strain softening at the high strain rates. The 2.25micrometer grain size samples showed strain softening at all strain rates. The microstructures of the strain hardened alloy showed dislocation activity in some aluminum-rich grains and rounding of the interphase boundaries. The samples deformed at the high strain rates showed little rounding of the boundaries and no dislocations. The 2.25micrometer grain size samples showed considerable rounding of the boundaries at low strain rates and less evidence of this at the higher strain rates. (Author)