遠心アトマイズした超合金粉末の性状について (粉末冶金<特集>)

概要

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Many kinds of Ni-base superalloys are used for the materials of engine parts of aeroplanes. Recently, superplastic formation techniques are utilized for the manufacture of turbine discs using HIP'ed and extruded Ni-base superalloy powders. For the turbine disc use, it is severely needed that the high temperature properties such as high temperature creep strength and low cycle thermal fatigue are so high. For this purpose, powders used are not contaminated with oxygen, organics and others, and the alloys such as γ/γ' precipitation strengthened Ni-base superalloys are becoming to be adopted.In this investigation we studied the relationship between characteristics of powder and operating conditions for the disc rotating-type centrifugal atomization of Ni-base superalloy. The results obtained were as follows.(1) The particle size mainly depends on the rotating speed and the diameter of the disc. As the rotating speed and the diameter increase, the particle size decreases. For example, the powder of mean diameter of 150μ is obtained at the rotating speed of 15000rpm and the disc diameter of 90mm.(2) The shape of powder particles mainly depends on the thermal conductivity of disc materials and also sort and amount of introduced cooling media. As the thermal conductivity becomes higher, the particles are inclined to be spherical, specially when helium is introduced.
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