抄録
It can be thermodynamically predicted that Si forms a stable gaseous monoxide and increases the refining effect under the reduced pressure in the same way as Ge. Therefore, the addition of Si may be expected to be effective for the improvement of magnetic properties of Fe–Ni alloys because of the decreasing gas content and non-metallic inclusions. From the above expectation, the effect of small additions of Si to 50 Ni–Fe alloy was investigated thermodynamically and magnetically. The results obtained are summarized as follows;
(1) It is theoretically deduced that Si more easily forms a gaseous monoxide under the reduced pressure and its vapor pressure attains about 102 mmHg at 1600°C. It can be, therefore, expected that Si is useful as a refining agent as is the case with Ge.
(2) The addition of Si causes a remarkable decrease in coercive force and a remarkable increase in initial permeability. The maximum permeability is highest near 1% Si. The critical frequency in effective permeability increases due to the addition of Si because of the increase in electrical resistivity.
(3) The addition of Si promotes remarkably the grain growth and it is particularly effective in the initial 1% Si. The grain size dependences of coercive force and initial permeability are experimentally given by the following expressions, irrespectitve of the Si content;
Hc=0.004+0.008⁄d, (d: mm)
and μ0=1.6×103+7.9×104d.
In the above relations, as the addition of Si makes d increase, Hc becomes smaller and μ0 larger.
