In the recent years, Nb_3Sn has been widely used for the development of high field superconducting magnets. It is known that the unreacted Nb-Sn composite undergoes a volume expansion during heat treatment due to the formation of the Nb_3Sn phase. In an as-received strand this expansion is isotropic. However, an anisotropic volume expansion was observed in the Rutherford-type cable samples. A systematic study was undertaken to investigate this phenomenon and to check the hypothesis that the plastic deformation of the strands during cabling process is responsible for this behavior. Nb-Sn strands from various manufacturing technologies were rolled down to different sizes, and the resulting thickness and width of the deformed strands wee measured before and after heat treatment. The results obtained on the deformed strands were then compared with those obtained from cables. A good consistency was achieved in most of the cases.
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