粉末冶金高速钢的精细结构

FINE SCALE MICROSTRUCTURES OF POWDER METALLURGY HIGH SPEED STEELS

应用分析电子显微术对粉末冶金高速钢的精细结构进行了研究。 Speed法萃取复型衍衬象研究结果表明,PT15和Rex25粉末冶金高速钢中二次析出碳化物的生长满足由扩散控制的生长动力学方程 PT15和Rex25钢中的二次析出碳化物与基体的取向关系与文献报道的取向关系相符。合金碳化物晶格常数的变化未导致新的取向关系。 MMD方法对Rex25钢的研究结果表明存在MC和M_2C伴生形核现象。MC碳化物择优在碳原子有序化的{100}_α面上形核。 应用会聚束电子衍射术对MC碳化物的点阵常数进行了测量。结果为a=4.2245 。高合金化没有导致MC自身结构和对称性的变化。

The fine scale microstructure of powder metallurgy high speed steels has been investigated by using analytical electron microscopy.The law of growth of secondary carbides in PT15 and Rex25 powder metallurgy high speed steels has been studied by replica electron microscopy. The growth of secondary carbides in PT15 and Rex25 obeys the equationwhich is controlled by diffusion.The relationship between the secondary carbides and ferrite are consistent with the orientation relationships reporied in literatures. The change in lattice parameter of secondary carbides caused by high alloying does not result in any new orientation relationship.MMD technique has been employed to study the coalescent nucleation of MC and M2C. Coalescent nucleation of MC and M2C. has found in Rex25 The advantage of nucleation of MC at the {100 a plans on which carbon atoms ordered has been discussed.The measurement of lattice parameter of MC was made by using CBED technique. The result is a=4.2245A. The structure and symmetry of MC do not change under high alloying.