| 초록 |
The ultrafine eutectic - primary dendrite composites have high yield strength as well as large plasticity. Recently, the addition of minor element leads to change the mechanical properties due to heterogeneities in length-scale of the microstructure. In the present study, the microstructural evolution and change of mechanical properties are investigated as increasing boron contents into Fe-Nb binary eutectic alloy. With addition of Boron from 0 atomic % to 10 atomic %, the lamellar eutectic structure drastically changes into a composite-type structure which consists of primary dendrites and bimodal eutectic. Furthermore, it is found that the pseudo-peritectic structure is observed with increase of Boron. Ultimately, the whole matrix is formed by pseudo-peritectic microstructure. Further increase Boron contents from 10 atomic % to 20 atomic %, the volume fractions of pseudo-peritectic structure decrease. Moreover, the matrix structure is dramatically changed. According to change of microstructure, the plastic strain was decreased with increase of yield strength from ~1.5Gpa to ~3Gpa by Boron addition. To understand about deformation behavior, fracture and lateral surface analysis are performed by Scanning Electron Microscopy and Atomic force microscopy. |
