| Title |
Microfracture Mechanism and Fracture Properties of Ni-Mn-Ga-Fe Ferromagnetic Shape Memory Alloys |
| Authors |
어광준(Kwang Jun Euh); 이정무(Jung Moo Lee); 남덕현(Duk Hyun Nam); 이성학(Sung Hak Lee) |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Ni-Mn-Ga-Fe; Magnetic shape memory alloy; Fracture toughness; Homogenization treatment; R-curve |
| Abstract |
The fracture toughness improvement of Ni-Mn-Ga-Fe ferromagnetic shape memory alloys containing ductile particles was explained by direct observation of microfracture processes using an in situ loading stage installed inside a scanning electron microscope (SEM) chamber. The Ni-Mn-Ga-Fe alloys contained a considerable amount of ductile particles in the grains after the homogenization treatment at 800~1100℃. γ particles were coarsened and distributed homogeneously along β grain boundaries as well as inside β grains as the homogenization temperature increased. The in situ microfracture observation results indicated that γ particles effectively acted as blocking sites of crack propagation, and provided stable crack growth that could be confirmed by the R-curve analysis. This increase in fracture resistance with increasing crack length improved overall fracture properties of the alloys containing γ particles. |