Research For Preparation And Thermal Stability Of Nanostructured Fe-Zr Based Alloy

High-temperature environment causes grain growth and the performance degradation in strength,hardness and other mechanical properties of nano-materials,which limits its processing routes as well as applications.The thermal stability researches are applied to strengthen the thermal stability of nanostructured metals through suppressin g grain growth of nano-materials bymeans of thermodynamic and kinetic approaches.In this paper,the developments in mechanism of thermal and kinetic theories have been briefly described,concerns arise from characterization methods(X-Ray diffraction(XRD),electron microscopy(SEM and TEM),focused ion beam(FIB),thermal analysis(TA),atomic probe technique(APT),etc)and thermal stability experiments of various nanostructured alloys mixed by limited kinds of metal elements(nanostructured Fe-based alloys,Cu-based alloy,Al-based alloy,etc)and complicate combination alloy(nanostructured steel alloy,oxide dispersion strengthened alloy,etc)are presented systematically,meanwhile,a summary for thermal stability of nano crystalline metals is put forward based on the analysis in the preceding part.It has been reported nanostructured Fe-Zr alloys show great thermal stability in passed researches,therefore,the Fe-Zr alloys are as the original material and objects of this study about preparation for nanocrystalline Fe-Zr based alloy.All the samples were prepared for the research about the effect of doping element and milling duration on fabrication of nanostructured alloy material from elemental powders blends of iron(purity:99.8%),zirconium(purity:99.9%),graphite(purity:99.98%),which were mechanically alloyed using planetary ball mill with stainless steel jars and balls.It has been found 30 h is the optimal milling duration under fixed ball to powder weight ratio(30:1)and rotation speed(300 rpm),the grain size of milled samples would rise in milling duration beyond 30 h.besides,doping content shows key influence on grain size of milled Fe-Zr samples.The grain size variation shows an incremental trend and a decrement one behind with increment C doping content from 0 to 8 at%in several milling duration?Spark plasma sintering is an effective sintering process for materials in powder,which has been applied for fabrication of nanostructured Fe-Zr block alloy by sintering the milled Fe-Zr powders in various temperature and duration.It turned out that this combination of 800 ? and 10 min is the optimal sintering environment under Aratmosphere when rate of temperature increase is 100 K/min,sintering pressure is 70 Mpa.