972 



THE BELL SYSTEM TECHNICAL JOURNAL, OCTOBER 1951 



MAGNET 



W 



-^FUSED QUARTZ 

 / RODS 



X 



r 



SPECIMEN / \""^^ 



-^POLYSTYRENE 

 SEALS 



GATE 

 N0.1 



CONTINUOUS 



WAVE 

 OSCILLATOR 



GATE 

 NO. 2 



VARIABLE 



MERCURY 



DELAY LINE 



TO 



DETECTOR 



Fig. 1 — Experimental arrangement for determining the elastic constants and AE 

 effect in single nickel crystals. 



Table I 

 Orientation and Elastic Constants 



Equation for Velocity 



V(cu + cii + 2 cu)/2p 

 • ^(cii — cii)/2p 



Measured 

 Velocity 

 (cm/sec) 



6.03 X 10»* 

 2.26 X 10» 

 3.65 X 10* 



Elastic constants 

 (dynes/cm*) 



CXI +cii+2cu=- 6.47 X 10>* 

 cii - cit= 0.90 X 10>2 

 c«= 1.185 X 10« 



A slight correction has been made for this value. 



The velocities for one demagnetized crystal' were found to have the values 

 shown by Table I. These values of velocity, and a density of 8.90 for the 

 single crystal, give values for the demagnetized elastic constants of 



Cll 



2.50, cn = 1.60, Cu = 1.185 



(3) 



all in 10'^ dynes/cm'^. 



To obtain the AE effect, the whole unit was placed between the jaws of a 

 large electromagnet. Since the crystal was about 2.5 centimeters in diam- 

 eter but only 0.472 cm thick, saturation could be obtained more easily 

 along the long directions of the crystal. Figure 2 shows the changes in 

 velocity of propagation along the [110] direction, caused by magnetization 



