Low-temperature deformability of brittle hard materials - new mechanical properties deduced from experiments with small-volume specimens

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H02300
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Structural/Functional materials
• Research Institution: Kyoto University
• Principal Investigator: INUI HARUYUKI 京都大学, 工学研究科, 教授 (30213135)
• Co-Investigator(Kenkyū-buntansha): 岸田 恭輔 京都大学, 工学研究科, 准教授 (20354178) ; 岡本 範彦 東北大学, 金属材料研究所, 准教授 (60505692)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 協調的原子集団励起 / プラストン / マイクロピラー / 試験片サイズ依存性 / 臨界体積 / 破壊靱性 / 核生成 / 収縮転位

Outline of Final Research Achievements

Low-temperature deformability has been investigated for brittle hard materials that do not exhibit deformability at ambient temperature in the bulk form, by means of micropillar compression testing. Low-temperature deformability is observed for SiC, some MSi2-type and M5Si3-type transition-metal silicides as well as for a sigma-phase intermetallic, an embrittlement phase in steels. But this was not the case for some ceramics such as B4C and Al2O3. As the specimen size decreases, the stress exerted to the specimen approaches to the stress necessary to generate dislocations. But, if the fracture toughness is not sufficiently high, failure occurs before the stress reaches the level for dislocation generation. The low-temperature deformability is concluded to occur more easily for brittle hard materials with higher fracture toughness because of the smaller critical notch size.

Free Research Field

材料物性