COMPRESSION TESTING OF SUPERPLASTIC LEAD-TIN EUTECTIC ALLOY AT ROOM TEMPERATURE

摘要

The deformation behavior of fine grained lead-tin eutectic alloy was investigated at room temperature using compression specimens at initial strain rates in the range 10~(-5) to 10~(-1) s~(-1). The grain size of the tested specimens was in the range of 2.8 to 7.2 μm. The results show that the flow stress- strain rate relation could be divided into two distinct regions. A superplastic region (region Ⅱ), which prevails at intermediate strain rates, has values of strain rate sensitivity, m and grain size exponent, p of 0.5 and 2.2, respectively. In dislocation creep region (region Ⅲ) that dominates at high strain rates values of m and p are 0.11 and 1.6, respectively, and the apparent activation energy is 45 kJmol~(-1). Region I that sometimes appears at low strain rates was not observed because a threshold stress is usually not present in high purity alloys such as the one used in this investigation.