اثر کار مکانیکی اولیه بر ساختار و ظرفیت تغییرشکل

EFFECT OF PRIOR WORKING ON THE STRUCTURE AND DEFORMATION CAPACITY

اثر کار مکانیکی اولیه بر ساختار و ظرفیت تغییرشکل آلیاژ Mn-29.5%Al-0.5%C

ABSTRACT

Alloys based on the system Mn–AI–C relate to promising magnetically hard materials which in magnetic properties in an anisotropic state are close to barium ferrites, and in magnetic energy referred to density, they markedly surpass widely known alloys of the YuNDK type . The high magnetic properties of the system Mn–Al–C are obtained as a result of plastic deformation . Metastable r-phase, governing the ferromagnetic properties of these alloys, is stable up to 700-750°C, and therefore deformation treatment of them is not carried out at higher temperatures. It should be noted that alloys of the Mn–AI–C system have high brittleness, low ductility, and poor workability. For example, in order to obtain magnets of these alloys by extrusion at 700°C a stress of more than 800 N/mm2 is required , which leads to rapid wear of the die tool. A study was made in  of alloys containing lamellar T-phase of the martensitic type obtained after air cooling. The morphology of the r-phase may be altered by using special working methods, e.g., extrusion  or prior plastic deformation as a result of which it is possible to expect a considerable improvement in the working capacity of the alloy. It is of interest to study prior deformation of an alloy of the Mn–AI–C system in the temperature region for existence of high-temperature e-phase followed by cooling.