Topic: Historical Perspective of Grain Boundary Research and Challenges toward Grain Boundary Engineering in the 21^st Century

Speaker: Prof.Tadao Watanabe

         Formerly Professor, Laboratory of Materials Design and Interface Engineering,
         Dept.of Nanomechanics, Graduate School of Eng., Tohoku University. Sendai, Japan
         Currently Honored Gust Scientist, Key Laboratory of Anisotropy and Texture of Materials,
         Northeastern University, Shenyang, China.

(Part I)

Time: 10:00-12:00 AM., (Wed.) Jun. 11, 2014

Venue: Room 403, Shi Changxu Building, IMR CAS

Abstract:

This lecture is consisted of two parts (Part 1, and Part 2) and is presented for graduate students and young researcher, expecting their future involvement in the recently established field of “Grain Boundary and Interface Engineering”. The concept was first proposed by the speaker as a new approach to “Materials Design and Development for Structural Materials with high strength and high fracture toughness”, from the early 1980s, later extended to “Functional Materials with high performance and a new function”, since the 1990s up to now.

Part I. Historical Perspective of Grain Boundary Research

Part I concerns “the historical perspective of grain boundary-related research” performed in order to reveal the effect of grain boundaries on bulk properties of polycrystalline materials, since the beginning of the last twenty century. However, particular interest and importance are of fundamental experimental studies of structure-dependent grain boundary properties, performed on orientation-controlled bicrystals of metals and alloys, intermetallics, semiconductor, and ceramics. The fundamental knowledge from bicrystal work was an origin of the concept of Grain Boundary Engineering, because it was found that almost all grain boundary properties strongly depend on the type and structure of grain boundaries whether they are special or general, i.e. of low-energy or high energy. In fact, polycrystalline material system is consisted of a grain boundary network of interconnecting of different types of grain boundaries in 1D, 2D and 3D spaces. It has been clarified that the effect of grain boundaries on bulk properties of polycrystalline materials can be never fully understood only by “effect of grain size”, i.e. “the density of grain boundaries” called “Hall-Petch effect” that has been long applied to the understanding of bulk properties, without knowledge of “grain boundary microstructures”.

Part II. Challenges of Grain Boundary Engineering, Past, Present, and Future

Since the time of the late 1970s, the characterization of individual grain boundaries was performed in bicrystals and polycrystals of metals and alloys. Of particular importance is the finding that there exists a significant heterogeneity of grain boundary-related phenomena such as grain boundary corrosion, segregation, precipitation, migration, sliding and fracture, depending on grain boundary character, the connectivity of different types of grain boundaries existing in polycrystalline materials. The necessity of quantitative and statistical data on the occurrence or presence of different types of grain boundaries was realized so that the grain boundary character distribution (GBCD) which was newly introduced by the speaker in 1980 at ICOTOM-6, by showing the result of quantitative determination of GBCD by using then newly developed SEM-ECP technique, for aluminium polycrystals produced by annealing of compressed single crystal sheets with different initial orientations. This kind of time-consuming task of characterization of grain boundary microstructure was replaced by the development of a modern SEM-EBSD/OIM technique by Brandt Adams and coworkers in the early 1990s. This enabled us to achieve and establish a new approach of Grain Boundary Engineering (GBE) in the past two decades. Now we can find how much bulk properties of polycrystalline structural and functional materials are decisively controlled by characteristics features of grain boundary microstructures. Accordingly there exists a high potential of manipulation of grain boundary microstructures through well designed material processing for advanced materials from metallic to ceramic materials. In Part 2, we introduce recent progress in GBE and its achievements, showing a number of examples of structural and functional materials with high performance and desirable properties, which never existed previously, before the application of GBE.

Overviews and Reviews on GBE by the speaker and coworkers.

1. Watanabe T: “An Approach to Grain Boundary Design for Strong and Ductile Polycrystals”, Res Mechanica, 11(1984), No.1, 47-84.

2. Watanabe T: “Grain Boundary Design for New Materials”, Proc. 4th Intern. Symp. on Grain Boundary Structure and Related Phenomena, Trans. JIM., 27(1986), 73-82.

3. Watanabe T: “The Potential for Grain Boundary Design in Materials Development”, Materials Forum, Commemorating Australia’s Bicentenary Volume, 11 (1988), 284-303.

4. Watanabe T: “Grain Boundary Design for Advanced Materials on the Basis of the Relationship between Texture and Grain Boundary Character Distribution”, Textures and Microstructures, 20(1993), 195-216.

5. Watanabe T: “Toward Grain Boundary Design and Control for Advanced Materials”, Proc. K. T. Aust Symp. on Grain Boundary Engineering, CIMMP, (1993), 57-87.

6. Watanabe T: “Grain Boundary Design and Control for High Temperature Materials”, Mater. Sci. Eng., A166 (1993), 11-28.

7. Watanabe T: “A Prospect of Grain Boundary Design and Control for Structural Materials”, Structural Materials: Engineering Application through Scientific Insight, as Proc. the Donald McLean Symp., 1995, ed. by Hondros E.D. McLean M: The Institute of Materials, (1996), 43-57.

8. Watanabe T, Tsurekawa S: “The Control of Brittleness and Development of Desirable Mechanical Properties in Polycrystalline Systems by Grain Boundary Engineering”, Acta Mater., 47(1999), 4171-4185.

9. Watanabe T: “Grain Boundary Engineering of Functional Materials in the 21st Century”, Ann. Chim. Sci. Mat., 27 (2002) Suppl.1, S327-S344.

10.Watanabe T, Tsurekawa S, Zhao X, Zuo L: “Grain Boundary Engineering by Magnetic Field Application”, Scripta Mater., 54 (2006), 969-975, View Point Set. No.40, “Grain Boundary Engineering”.

11.Watanabe T, Tsurekawa S, Zhao X, Zuo L, Esling C: “A New Challenge: Grain Boundary Engineering for Advanced Materials by Magnetic Field Application”, J. Mater. Sci., 41 (2006), 7747-7759.

12.Watanabe T: “The Coming of Grain Boundary Engineering in the 21st Century”, Microstructure and Texture in Steels and Other Materials, ed. by Haldar A, Suwas S, Ghattcharjee D: Springer, (2009),Chap.4, 43-82.

13. Watanabe T: “Grain Boundary Engineering: Historical Perspective and Future Prospects”, J. Mater. Sc., 46 (2011), 4095-4115.

14.Watanabe T: “The Advent and Recent Progress of Grain Boundary Engineering (GBE): In Focus on GBE for Fracture Control through Texturing”, Microstructural Design of Advanced Engineering Materials, ed. by Molodov D. A, Wiley-VCH, (2013), Part IV, Chap.11, 405-446.