29th Symposium on Fusion Technology (SOFT 2016)

P2.184 Development of Oxide dispersion strengthened-Copper using MA-HIP process

6 Sep 2016, 14:20

1h 40m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 184

Poster I. Materials Technology P2 Poster session

Speaker

Hiroyuki Noto (National Institute for Fusion Science)

Description

Copper (Cu) alloy is a candidate materials for use as heat sink materials of fusion divertor because of its good thermal conductivity. In recent years a number of studies have been carried out on Cu-based materials such as Precipitation Strengthened Cu (PS-Cu).However, the material has some critical issues such as instability of microstructure at high temperature and loss of strength by irradiation induced softeing and hardening. On the other hands, conventional dispersion strength (DS)-Cu such as GlidCop^®® (Cu-Al2O3) is known to have higher stability in microstructure at high temperature than PS-Cu. These conventional DS-Cu, which have been produced by internal oxidation and extrusion, may cause coarsening of the dispersed particles, inhomogeneity in microstructure and anisotropy in mechanical properties. 　In this study, a new DS-Cu alloy was fabricated by combination Mechanical Alloying (MA) and Hot Isostatic Pressing (HIP) method. This alloying-sintering technique is well known as a technique which can enhance mechanical properties at high temperature. A good example is seen in Oxide Dispersion Strengthened Steel. Therefore, we expect that MA-HIP process can offer technical advantages for DS-Cu. 　Examination of the particles after MA shows that the grain size and Vickers hardness decreased and increased, respectively with the increase in MA time. The mechanical alloyed copper from 8 hr to 32hr exhibited different electrical resistivity. This results suggest that the microstructure and the strengthening mechanism have changed between 8 and 16 hr of the MA process. At MA time of 32 hrs, the hardness was comparable to that of Glidcop^®® although the grain size is much larger. In result of the texture observation using TEM, equiaxed-grains which contained nano-particles with high Al levels were observed. These results implied that the precipitate hardening took place for the alloy more significantly than that for Glidcop^®®.