Ni 基超耐熱合金 IN-100 の凝固挙動

概要

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Solidification behavior of IN-100 and effect of alloying elements on it were investigated by means of differential thermal analysis (DTA), microstructural observation, X-ray diffraction, and EPMA analysis. In alloy IN-100, it was revealed that six phase reactions took place successively during cooling from melt. These reactions and the onset temperatures were as follows, 1) L→γ(1329℃), 2) L→γ+MC(D) (1319℃), 3) L→γ+MC(ID) (1310℃), 4) L→γ+γ′(1259℃), 5) γγ′→(1210℃), and 6) L→γ+M_3B_2(1200℃), where L is melt, γ is fcc phase. MC(D) and MC(ID) denote MC carbides formed among dendrite arms and interdendritic regions, respectively. γ′is Ll_2 type ordered phase and M_3B_2 denotes boride phase. The occurrence of two kinds of carbide reactions ((2) and (3)) and M_3B_2 eutectic reaction ((6)) was identified for the first time in this study. SEM observation on the carbides, which were embossed on the γ matrix by an electrolytic etching, showed that the carbides had three types of morphology. These were blocky, lattice-like and flaky in shape. It was found that the blocky carbides were contained in MC(D), while the lattice-like and flaky carbides were frequently found in MC(ID). The influence of C, Al, Ti, and B on the above phase reactions and solidified structure was also clarified.
社団法人日本鉄鋼協会の論文
1985-01-01