Search

Ti--10V--2Fe--3Al alloys exhibit shape memory (SM) and reverse shape memory (RSM) effects. When an alloy sample that has been strained by external force at room temperature is heated, the strain recovers and SM effect develops at around 300, but as the temperature increases further, the shape changes in the opposite direction due to RSM effect at around 450. This RSM effect has potential applications in forming processes such as thin--walled pipes, but has the disadvantage that the RSM treatment makes the material very brittle. Therefore, in this study, a heat treatment to restore toughness while maintaining the shape after forming was investigated. The alloy quenched from 1050 had a microstructure consisting of a β matrix phase and αAA--martensite (αAAMq). Differential scanning calorimetry (DSC) results showed that the continuous heating process occurred in the following order: αAAMq → β reverse transformation, ω formation, ω disappearance, thermally induced αAAiso phase formation, α precipitation and α → β transformation. Ageing at 300, where the SM effect appears, caused significant embrittlement due to the formation of the ageing ω phase. Ageing treatment at 450, where the RSM effect is obtained, resulted in the formation of a fine α phase, which also caused significant embrittlement. On the other hand, additional aging at 600 for 1.8 ks after RSM treatment significantly improved the toughness and produced material properties comparable to aerospace material specifications. It was found that the embrittlement in the RSM treatment was due to the precipitation of fine α phase, and that the growth of α phase with a width of about 0.2µm or more was required for toughness recovery. It was also found that the specimen shape formed by the RSM treatment hardly changed after the additional heat treatment of 1.8 ks at 600. [ABSTRACT FROM AUTHOR]

In recent years, attention has focused on the excellent mechanical properties of bones, teeth, and crustaceans. In particular, interlocking tissue is strongly interested as one of the characteristics of the microscopic structure of crustaceans. The interlocking structure has sutures like puzzle pieces, and friction slip in the pull-out process occurs at the sutures by subjecting to a tensile load. As a result, it is recognized that the toughness is apparently improved. By the way, in wooden houses in Japan, iron nails are not used, but the mortise-neck joints are used to fasten timbers together. The feature is that the fastening force can be freely controlled by adjusting the angle of the suture. Therefore, in this study, we simulate the bioinspired interlocking structure by these sickle joints and develop a mechanical model based on the pull-out mechanism for this structure. In order to verify the validity of the developed model, we compared it with the finite element analysis results. Furthermore, we investigated the effect of the suture shape on the relationship between load and displacement. It was clarified that the suture shape and interfacial friction coefficient affect the maximum load and elongation at break. Finally, the relationship between the fracture energy estimated from the relationship between load and displacement and these parameters was summarized as a map.

The effect of immersion in juice from Iwateyamanashi (Japanese wild pear) varieties that mature at different times on the toughness of bovine muscle was investigated. Muscle tissue was obtained from Japanese Shorthorn steers (n = 5). Fruit from three pear varieties was used : i1302, an early variety that matures in July ; i1515, a mid-season variety that matures in August ; and, i0218, a late variety that matures in October. Two treatment groups were established : pre-heated juice, and unheated juice from each variety. For the first group, the juice was heated at 90°C for 10 minutes and then cooled on ice. Juice in the second group was not heated. In both treatment groups, the muscle samples were immersed in juice at 40°C for 1 hour and then heated to 80°C for 3 minutes. The textural properties of the muscle samples were then analyzed. Maximum load and load of gumminess of samples immersed in the unheated i1515 juice group were significantly lower than those in the heated juice group. There were no significant differences in cohesiveness of samples between groups. Nor were there any significant differences in drip loss, cooking loss, and total loss of samples between groups. These results suggested that beef could be tenderized without lowering water holding capacity by immersion in the juice of the i1515 variety of Iwateyamanashi. [ABSTRACT FROM AUTHOR]

Copyright of Nihon Chikusan Gakkaiho is the property of Japanese Society of Animal Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)