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Materials Frontier No.146

Title: Micropillar Compression Testing as a Vehicle to Understand Deformation Behavior and 

        Mechanisms of  Materials of Interest for Structural Applications 

Speaker: Haruyuki Inui          http://imc.mtl.kyoto-u.ac.jp/index.html

Date/Time: 2014-08-06,14:00 

Venue: Room.312,MaterialBuildingD

Inviter: Prof.Di ZHANG

Contacts:Prof.Dingbang XIONG   xiongdingbang@sjtu.edu.cn,021-54742348


Since the discovery of the testing method by Uchic et al. in 2004, micropillar compression tests have extensively been used to explore the deformation mechanisms of small volumes, in most cases, of metallic materials with fcc (face-centered cubic), bcc (body-centered cubic) and, to a lesser extent, hcp (hexagonal close-packed) structures. Significant progress has been made in recent years in understanding the deformation behavior of small volumes of these metallic materials. In particular, the specimen-size dependent strength has been proved to arise from the size-dependent operation stress of the weakest single-arm dislocation sources due to the stochastics of dislocation source lengths. Apart from this, we have utilized the micropillar testing method to evaluate the deformation behavior and mechanisms (identification of slip systems, deduction of critical resolved shear stress and dislocation dissociation modes) of materials that cannot be prepared easily in the single-crystalline form and that cannot be plastically deformed at ambient temperature in the bulk form. Those include LPSO (long-period stacking order) phases in Mg-Zn-Y system and the ζ (FeZn13) phase in the Fe-Zn system for the former category and MoSi2 and SiC for the latter category in the presentation. Based on the results obtained, the validity of various models to explain the specimen-size dependent strength of micropillar compression specimens will be discussed.

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