| 摘要 |
PURPOSE:To obtain the polycrystal having excellent heat conductivity even at the temperature of liquid nitrogen or below by a method wherein the surface of the alloy powder, consisting of the rare-earth element such as Y, lantanides element and the remainder composed of Ni, Co, Fe and the like, is coated by the layer consisting of high density Ni, Co, Fe and the like, and they are coupled by a non-magnetic metal binder. CONSTITUTION:Fe2, Ni2 and Co2 are dissolved in an arc furnace, the obtained alloy is pulverized and formed into fine powder. At this time, the grain diameter of the powder is selected in the range of 1-10mum taking into consideration of the rate of filling of said powder and the binder to be used later. Also, the content of the rare- earth element such as Y, lanthanides element and the like contained in said magnetic alloy is set in the range of 20-99 wt. %, and when the content is lowered, magneto- caloric effect can not be obtained, and when it is too much, the characteristics of pulverization is deteriorated, and the manufacture of the magnetic polycrystal becomes difficult. Also, Gd, Tb, Dy and the like are contained in order to obtain excellent magneto-caloric effect. Subsequently, the surface of the powder is coated by the layer of high density Ni, Co, Fe and the like, and they are coupled using the non-magnetic metal binder such as Au, Cu and the like. |
