2004 年 45 巻 1 号 p. 65-68
Phase transformation in austenitic 301 stainless steel was studied under 300 keV Fe+ and Ar+ ions implantations to fluence of 1×1021 ions m-2 at room temperature, in order to pursuit the nucleation of martensitic phase transformation in ion-implanted region. Microstructures after ion implantation were observed by transmission electron microscopy (TEM) with plane view and for cross-sectional specimens. The plane view observation of the implanted specimen showed that phase transformation from the γ phase to α phase was induced due to implantation to doses of 5×1020 Fe+ ions m-2 and 1×1020 Ar+ ions m-2. The nucleation of implantation-induced phase increased with increasing of fluence. The orientation relationship between the γ matrix and the induced α phase was identified to be (110)α || (111)γ and [111]α || [011]γ, close to the Kurdjumov-Sachs (K-S) for the Fe+ ion implanted specimen, and (110)α || (111)γ and [001]α || [011]γ close to the Nishiyama-Wasserman (N-W) for the Ar+ ion implanted specimen. The cross-sectional observation after implantation revealed that the phase transformation preferentially nucleated in the region near the surface in metal (Fe+) ion implanted specimen, because the gradient of implanted ion concentration attains maximal near the surface. On the other hand, the behavior of phase transformation in the Ar+ ion implanted specimen was different from that of Fe+ ion implantation and the phase was induced at deeper region from surface than Fe+ ion case.
