METHOD FOR PRODUCING SEMI-FINISHED PRODUCTS FROM NITI SHAPE MEMORY ALLOYS

摘要

Disclosed is a method for producing semi-finished products from a shape memory alloy, particularly an NiTi shape memory alloy, wherein a powder is first produced from a shape memory alloy, and subsequently the powder is divided into a coarse fraction and a fine fraction in a separating cut T. While the fine fraction is required, in particular, for the production of a first semi-finished product, employing the metal injection molding (MIM) method, the coarse fraction can be used for the production of a second semi-finished product, employing the hot isostatic pressing (HIP) method. The advantages of the invention can be summarized as follows. The MIM method for producing semi-finished products from a shape memory alloy is qualitatively improved and more cost-effective to implement if the coarse fraction that is typically obtained during powder production, but not used for the MIM process, can advantageously be supplied to a further process, in this case the HIP process. Due to the use of particularly fine powder, the semi-finished products produced by way of the MIM method have an advantageous, powder-metallurgical microstructure. In particular, the alloying elements are distributed particularly homogeneously in these semi-finished products, casting flaws or segregations do not usually occur, no anisotropy of the structure occurs as a result of the processing steps, and ternary alloys can be processed, which due to the mechanical properties thereof, cannot be processed by way of conventional forming methods.