Si_3N_4ウイスカーあるいは粒子で強化した6061アルミニウム複合材料の高ひずみ速度領域における超塑性挙動

概要

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Aluminum matrix (6061) composites reinforced with either whiskers or particulates of Si_3N_4 were processed under the same hot extrusion conditions, and their superplastic properties have been compared in constant strain rate tension tests at a constant temperature of 818 K. Large elongations from 400 to 450% were observed at a high strain rate range from 10^<-1> to 1 s^<-1> in the Si_3N_<4p>/6061Al composite. For the Si_3N_<4w>/ 6061Al composite, on the other hand, a similar value of about 450% elongation was obtained at a lower strain rate of 4×10^<-2>s^<-1> than that for the Si_3N_<4p>/6061Al composite. Grain sizes were about 2μm for the Si_3N_<4p>/6061Al composite and about 3μm for the Si_3N_<4w>/6061Al composite. High strain rate superplasticity of both composite may be attributed to fine grained structures. On the true stress-true strain curves of the Si_3N_<4w>/6061Al composite, strain hardening was observed over almost entire part of elongation during superplastic flow. For the Si_3N_<4p>/6061Al composite, on the other hand, the near steady state of flow stress or strain softening was found, suggesting a difference in micro-structural evolution during superplastic flow between these composites.
社団法人日本セラミックス協会の論文
1992-04-01