TY - JOUR
T1 - Effects of microstructure on superplastic behavior and deformation mechanisms in β-silicon nitride ceramics
AU - Zhan, Guo Dong
AU - Mitomo, Mamoru
AU - Ikuhara, Yuichi
AU - Sakuma, Taketo
PY - 2000/1/1
Y1 - 2000/1/1
N2 - The influence of grain shape and size on superplastic behavior and deformation mechanisms was investigated in annealed β-silicon nitride materials and compared with the results for hot-pressed material. The microstructure of the annealed materials consisted of fine equiaxed β-grains together with some elongated ones. Similar to the deformation behavior in the hot-pressed material, strain hardening did not occur in these annealed materials. Moreover, in contrast to the deformation behavior under tension, grain alignment under compression resulting from the development of a mild texture did not give rise to strain hardening. An annealed material with small elongated grains had a flow-stress dependency of n = 1, whereas other annealed materials with large elongated grains exhibited a flow-stress dependency of n = 1.6. In terms of texture development and the effect of grain shape on the creep rate when diffusion was the rate-controlling mechanism, a single curve with a stress exponent of approx. 1 and a grain-size exponent of 3 were obtained for all materials. This suggests that the deformation mechanism in these annealed materials was the same as that of fine equiaxed β-silicon nitride.
AB - The influence of grain shape and size on superplastic behavior and deformation mechanisms was investigated in annealed β-silicon nitride materials and compared with the results for hot-pressed material. The microstructure of the annealed materials consisted of fine equiaxed β-grains together with some elongated ones. Similar to the deformation behavior in the hot-pressed material, strain hardening did not occur in these annealed materials. Moreover, in contrast to the deformation behavior under tension, grain alignment under compression resulting from the development of a mild texture did not give rise to strain hardening. An annealed material with small elongated grains had a flow-stress dependency of n = 1, whereas other annealed materials with large elongated grains exhibited a flow-stress dependency of n = 1.6. In terms of texture development and the effect of grain shape on the creep rate when diffusion was the rate-controlling mechanism, a single curve with a stress exponent of approx. 1 and a grain-size exponent of 3 were obtained for all materials. This suggests that the deformation mechanism in these annealed materials was the same as that of fine equiaxed β-silicon nitride.
UR - http://www.scopus.com/inward/record.url?scp=0034508315&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034508315&partnerID=8YFLogxK
U2 - 10.1111/j.1151-2916.2000.tb01701.x
DO - 10.1111/j.1151-2916.2000.tb01701.x
M3 - Article
AN - SCOPUS:0034508315
VL - 83
SP - 3179
EP - 3184
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
SN - 0002-7820
IS - 12
ER -