In the seventies some scientific workers from France and Italy suggested that the grain boundary internal friction peak (named the K (e) over cap peak in the literature) widely accepted as a grain boundary process, is...In the seventies some scientific workers from France and Italy suggested that the grain boundary internal friction peak (named the K (e) over cap peak in the literature) widely accepted as a grain boundary process, is originated from the motion of lattice dislocations. Since this problem is one of fundamental importance, this controversy has drawn much international attention. Started from 1982, the Hefei research group made a critical analysis of the large amount of literature concerning this problem and,performed a series of crucial experiments to clarify the controversy. It is concluded that the irrelevant evidence suggested by the controverters comes from the farfetched interpretation and the mis-identification of the internal friction peaks appeared under various experimental conditions and different states of the specimens.展开更多
Internal friction and modulus measurements of nano ZrO_2 solids for different particle sizes (including original compacted and annealed samples) were systematically carried out from room temperature to -200℃. It was ...Internal friction and modulus measurements of nano ZrO_2 solids for different particle sizes (including original compacted and annealed samples) were systematically carried out from room temperature to -200℃. It was found that the three peaks (P_1, P_2 and P_3 corresponding to ascending measurement, or P_1~', P_2~' and P_3~' corresponding to descending measurement) appeared. By investigating the behavior of internal friction peaks (P_1, P_2, P_3 orP_1~' P_2~', P_3~'), it is indicated that the origin of peak P_3 or P_3~' can be attributed to grain boundary relaxation, that is, it is caused by slip of the grain boundaries in nano ZrO_2 solids. The peak P_2 (or P_2~')and P_1 (or P_1~') may possibly be associated with phase transformation of nano ZrO_2 solids at low temperature range. The energy dispersion decreases and the modulus increases notably with the increase in annealing temperature of the nano samples.展开更多
文摘In the seventies some scientific workers from France and Italy suggested that the grain boundary internal friction peak (named the K (e) over cap peak in the literature) widely accepted as a grain boundary process, is originated from the motion of lattice dislocations. Since this problem is one of fundamental importance, this controversy has drawn much international attention. Started from 1982, the Hefei research group made a critical analysis of the large amount of literature concerning this problem and,performed a series of crucial experiments to clarify the controversy. It is concluded that the irrelevant evidence suggested by the controverters comes from the farfetched interpretation and the mis-identification of the internal friction peaks appeared under various experimental conditions and different states of the specimens.
基金Project supported by Laboratory of Internal Friction and Defects in Solids, Academia Sinica
文摘Internal friction and modulus measurements of nano ZrO_2 solids for different particle sizes (including original compacted and annealed samples) were systematically carried out from room temperature to -200℃. It was found that the three peaks (P_1, P_2 and P_3 corresponding to ascending measurement, or P_1~', P_2~' and P_3~' corresponding to descending measurement) appeared. By investigating the behavior of internal friction peaks (P_1, P_2, P_3 orP_1~' P_2~', P_3~'), it is indicated that the origin of peak P_3 or P_3~' can be attributed to grain boundary relaxation, that is, it is caused by slip of the grain boundaries in nano ZrO_2 solids. The peak P_2 (or P_2~')and P_1 (or P_1~') may possibly be associated with phase transformation of nano ZrO_2 solids at low temperature range. The energy dispersion decreases and the modulus increases notably with the increase in annealing temperature of the nano samples.
