Chen J S, Poirier D R, Damento M A, Demer L J, Biancaniello F, Cetas T C
Department of Materials Science and Engineering, University of Arizona, Tucson.
J Biomed Mater Res. 1988 Apr;22(4):303-19. doi: 10.1002/jbm.820220405.
Ferromagnetic alloys, used in the form of "thermoseeds" for surgical implantation, have been developed and used to induce localized hyperthermia in cancerous growths. Alloys of nickel with approx. 4 wt.% Si were chosen for this study because they have Curie temperatures in the desired range of 45-60 degrees C. The thermoseeds were prepared by using either a special casting technique or casting and swaging followed by homogenization. The effects of these different processing schedules on the magnetic behavior of these alloys are discussed. In particular, the importance of minimizing oxidation during melting and heat treating, and the effects of homogenizing the thermoseeds on the relative permeability at temperatures near the Curie temperature are pointed out. The best processing schedule is casting small ingots while avoiding oxidation, followed by swaging, drawing, and homogenization. Actual induction heating experiments and the results from magnetization tests indicate that Ni-4 wt.% Si alloys prepared in this manner can be used as thermoseeds with predictable Curie temperatures. These thermoseeds can be used to obtain nearly uniform and constant temperatures in tumors with variable blood flows.
用于手术植入的“热籽”形式的铁磁合金已被研发并用于在癌性肿瘤中诱导局部热疗。本研究选用了含约4 wt.%硅的镍合金，因为它们的居里温度在45 - 60摄氏度的理想范围内。热籽通过特殊铸造技术或先铸造再锻造然后进行均匀化处理来制备。讨论了这些不同加工工艺对这些合金磁性能的影响。特别指出了在熔化和热处理过程中尽量减少氧化的重要性，以及热籽均匀化对居里温度附近温度下相对磁导率的影响。最佳加工工艺是铸造小锭坯同时避免氧化，随后进行锻造、拉拔和均匀化处理。实际感应加热实验和磁化测试结果表明，以这种方式制备的Ni - 4 wt.%硅合金可用作具有可预测居里温度的热籽。这些热籽可用于在血流变化的肿瘤中获得几乎均匀且恒定的温度。
