Abstract A temperature sensitive element comprises fine grain powders which consist of a spin reorientation type ferromagnetic material having a transition temperature range, below which transition temperature range the easy direction of magnetization of the spin reorientation type ferromagnetic material is predetermined in one crystallographic direction thereof and above which transition temperature range the easy direction of magnetization is a predetermined other direction perpendicular to the predetermined one crystallographic direction. The temperature sensitive element is produced by compacting the fine grain powders of a spin reorientation type ferromagnetic material at a temperature higher than the transition temperature range. A polycrystalline rare earth cobalt alloy material made in accordance with the invention can now be used in the field where low Curie point ferrite or where bimetals have been used previously for a thermal valve or a temperature controlling device.
A process according to claim 1, wherein said spin reorientation type material is a rare earth cobalt alloy material generally expressed by a formula of RCo 5 , wherein the R component is one rare earth element selected from a group consisting of neodymium (Nd), dysprosium (Dy), and terbium (Tb) and the Co component consists of cobalt or is cobalt and an additive metal which partly replaces the cobalt.
Claim 2
Dependent Claim
25 words
A process according to claim 1, wherein said transition temperature range falls within a temperature range of from room temperature to 150° C. (425° K.).
Claim 3
Dependent Claim
20 words
A process according to claim 2, wherein the heating temperature in said heating step slightly exceeds said transition temperature range.
Claim 4
Dependent Claim
70 words
A process according to claim 3, wherein the spin reorientation type ferromagnetic material is a rare earth cobalt alloy material generally expressed by a formula of RCo 5 , wherein the R component is one rare earth element selected from a group consisting of neodymium (Nd), dysprosium (Dy), and terbium (Tb) and the Co component consists of cobalt or is cobalt and an additive metal which partly replaces the cobalt.