The Effect Produced on the Property of the Sintered NKS Permanent-Magnets by Addition of Boron, Phosphorus, Zirconium and Titanium; and the Yield of Aluminum

Abstract

Studies were made, in 'order to improve the magnetic property of the sintered NKS permanent-magnets by using vacuum sintering technique, of the effect produced on it by addition of the above mentioned agents, to find their magnetic property, sintered density, hardness, dimentional changes, and microstructure. The addition of the above mentioned elements improves the quality of the sintered NKS permanent-magnets remarkably. The addition of boron or phosphorus causes grain growth in the structure of the magnets, and an eutectic structure appears in the grain boundary when the boron or phosphorus is added to excess in quantity. This grain growth scarcely appears in the structure by the addition of titanium but does appear when zirconium is added.The yield of aluminum is 90-95% when 8-15%(wt) of aluminum is added, and increases straightly with the quantity of aluminum. Accordingly the loss of aluminum is 10-15% (wt). The lost of aluminum has mostly changed into aluminum-oxide by sintering process in low vacuum and remains as such in the magnets, but vaporizes by sintering process in high vacuum.