283 
1 908—9. ] Magnetic Properties of certain Copper Alloys. 
the composition copper 60 per cent., manganese 25 per cent., aluminium 15 
per cent.* 
Simple Bronzes, Manganese, and Aluminium . — With a view to throw- 
ing some light on the magnetic properties of the Heusler alloy, tests were 
carried out on the alloys (4)-(8) already mentioned, and on pure manganese 
and aluminium. These materials were magnetised with a field of 4400 C.G.S. 
units, and their permanent magnetism was subsequently measured. Tests 
were also made with the specimens surrounded with liquid air and thus 
cooled to —190° C., and the whole procedure was thereafter repeated with 
the material quenched at 500°-600° C. In the accompanying table the results 
are given and compared. The results obtained with similar specimens were 
Intensity of Magnetisation. 
Percentage 
Composition of 
Cast Material. 
Quenched Material. 
No. 
Material. 
Magnetised at 
Magnetised at 
Cu. 
Mn. 
Al. 
Ox 
0 
O 
- 190° C. 
h- » 
Cn 
o 
p 
- 190° C. 
4 
95 
5 
■010 
091 
029 
•no 
5 
90 
10 
•184 
•228 
•145 
175 
6 
40 
60 
2 
2 
2 
2 
7 
30 
70 
2 
2 
•021 
•027 
8 
70 
30 
•057 
•072 
•096 
•118 
9 
... 
100 
2 
2 
2 
2 
10 
... 
100 
4 - 76 
4-68 
3 74 
3-70 
1 indicates that the value of I is less than 0‘Q1. 
in excellent agreement, and hence the percentage changes occurring between 
the separate tests on any specimen are thoroughly reliable. At the same 
time, owing to the uncertainty as to the exact dimensions of the specimens, 
their polar separation, and their distance from the magnetometer needle, the 
absolute values tabulated for I are only approximate. They are given as 
indicating the order of the intensity of magnetisation, and as affording a 
convenient method of comparing the properties of the different materials. 
In the “ Eighth Report of the Alloys Research Committee ” are given the 
equilibrium curves of the copper-aluminium alloys.-]- It will there be found 
that (a) the 5 per cent, aluminium-bronze is a solid solution of aluminium 
in copper, ( b ) the 10 per cent, aluminium-bronze is a mixture of Cu 4 Al and 
* Physical Review , vol. xxi. p. 335. 
t Proc. Inst. Mech. Eng., 1907, p. 204. 
