Time of isothermal holding in the course of in-air heat treatment of soft magnetic Fe-based amorphous alloys and their magnetic properties

Effect of parameters of heat treatment on magnetic properties and magnetization distribution in ribbons of amorphous soft magnetic iron-based alloys

“…Based on Fig. 3, which displays a dependence of the maximum magnetic permeability of samples of the amorphous soft magnetic Fe 77 Ni 1 Si 9 B 13 alloy on the relative dura tion of isothermal holding τ/τ opt during in air heat treatment at 410°C with τ = 5 min and a cooling rate of 15 K/min, it can be seen that μ max depends slightly on the relative duration of isothermal holding down to adjusting dimensions and is equal to 1 min -1/3 (this value of α is obtained at х = 0.836) [3]. It can be seen that, in the temperature range of 360-380°C, at α < 0.07, the upper boundary of the range corresponds to a ratio of the temperature of heat treatment to the crystallization temperature ~0.72 and the ratio τ/τ opt is less than 0.1 (Fig.…”

“…) at these temperatures [3]. In addition, the increased cooling rate brings about a reduction in μ max and is mainly caused by the increase in the relative volume of domains with the orthogonal magnetization as the strongest factor that stabilizes the walls of domains with the planar magnetization.…”

“…This made it possible to vary the degree of activity of diffu sion processes in a wider temperature range [3]. The studied samples were in the form of strips with dimen sions of 100 × 10 × 0.022 mm.…”

“…All the processes occurring upon in air heat treatment are diffusive. The their activity course is primarily con nected with the isothermal holding temperature [2,3], and heating and cooling rates are very impor tant parameters. Since the actions of the last two fac tors on the formation of the level of magnetic proper ties after in air heat treatment were studied to a lesser extent and manifest thenselves most pronouncedly at a comparatively low level of internal stresses, in this work, we investigated the effect of the isothermal holding temperature and cooling rate on the magnetic properties and magnetization distribution in ribbons of amorphous soft magnetic iron based alloys.…”

“…Samples of the amor phous Fe 77 Ni 1 Si 9 B 13 alloy were heat treated in air at 360-430°C with cooling rates of about 15 and 40 K/min. Since the level of magnetic properties after annealing depends on the magnetization distribution in the initial state of the ribbon [1,3], for the investi gations, we chose samples with a uniform distribution of magnetization in the initial (quenched) state. The magnetization distribution was determined according to the procedure we developed [4].…”