Kazutaka Mukoyama

Construction of Electronic Factual Database on Very High Cycle Fatigue Properties for Structural Metallic Materials

As a joint project of Committees on Fatigue and Reliability Engineering in the Society of Materials Science, Japan (JSMS), an electronic database on fatigue strength of metallic materials fabricated in Japan had been constructed and published in 1996. Book style of the same data compilation had been published at the same time by the JSMS and Elsevier. About twenty years have passed since the above publications of database and databook. Thus, a lot of new fatigue test data have been obtained during such a long period including many data on the very high cycle fatigue such as gigacycle regime. Based on such a circumstance, the JSMS has organized a new project to construct an electronic database on very high cycle fatigue. A lot of numerical data obtained by fatigue tests would be compiled together with many photographs of fracture surfaces. In this paper, fundamental view and compilation concept of the database are briefly introduced by showing a typical example of proto-type database constructed from domestic data in Japan.

Generation Mechanism of Internal Stress of BN Films Prepared by Ion Mixing and Vapor Deposition

It has been widely recognized that the successful formation of cBN phase requires a bombardment of growing films with energetic ions. However, the intensive ion bombardment also causes high compressive internal stress during formation of film and decreases adhesion performance. The molecular dynamics analysis was applied to investigate the generation mechanism of internal stress in BN film prepared by ion mixing and vapor deposition (IVD) technique. Firstly, projection analysis was carried out as changing the acceleration voltage of N ion. After projection analysis, relaxation of target was carried out under constant pressure by Parrinello‐Rahman method. As a result, during projection analysis, the formation of sp3 bonds was observed and cubic structure was generated by transition of crystal structure from rhombohedral. After relaxation of target, an increase of volume of unit cell was observed. Therefore, it is concluded that the high internal compressive stress of cBN film is caused by increase of volum...