Microstructural evolution of materials with hierarchic structure and their strength

2016 Fiscal Year Final Research Report

• Project/Area Number: 26289256
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Structural/Functional materials
• Research Institution: Nagoya University
• Principal Investigator: Murata Yoshinori 名古屋大学, 工学(系)研究科(研究院), 教授 (10144213)
• Co-Investigator(Kenkyū-buntansha): 山本 剛久 名古屋大学, 工学(系)研究科(研究院), 教授 (20220478)
• Co-Investigator(Renkei-kenkyūsha): KOYAMA TOSHIYUKI 名古屋大学, 大学院工学研究科, 教授 (80225599)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: ミクロ組織 / 耐熱鋼 / ニッケル基超合金 / フェーズフィールド法

Outline of Final Research Achievements

The relationship between hierarchic microstructure evolution and the creep strength was investigated using both heat resistant steels and nickel-based superalloys with the aid of phase-field simulation and a series of experiments. It was found that the lath structure collapsed with the segregation of dislocations, which were formed inside the lath by the martensite transformation, and that the segregated dislocations became sub-boundaries in steels. The boundary energy should become the driving force for the microstructure evolution from the lath and block morphology to the granular sub-boundary morphology.
In Ni-based single crystal superalloys, it was found by the phase field simulation that the alloy having irregular array of the cubic gannma-prime phase gave much higher creep strain rate than that having orderly array of the cubic gannma-prime phase. As a result, it was concluded that inhomogeneous microstructure became trigger of the acceleration creep in metallic materials.

Free Research Field

金属材料組織学