Microstructure and Mechanical Properties of Nano-structured Al-8Fe-2Mo-2V-1Zr Alloys Fabricated by Melt Spinning and Extrusion

초록

Melt spinning process has been well known as one of rapid quenching techniques those cooling rates are faster than 106K/s and therefore would be effective method in order to produce a nano-sized microstructure or amorphous structure. Moreover, we could control an extremely fine microstructure containing dispersoids readily in terms of rapid quenching and subsequent heat treatment at desirable temperatures in certain alloys with even narrow solubility for alloying elements. In this study, melt spun ribbons were prepared by single roll melt spinner with a copper roll speed of 42m/sec, and then we pulverized melt spun ribbons to make a fine powders using a speed rotor mill. The pulverized powders were pre-compacted in an aluminum can and then hot-extruded at 648K in the extrusion ratio of 5:1. The microstructure and mechanical properties of nano-structured Al-8Fe-2Mo-2V-1Zr alloys fabricated by melt spinning and hot extrusion were investigated in terms of OM, TEM and compressive test. Equiaxed structure with average grain size of 50nm was characterized in the hot-extruded sample. Well-defined dispersoids based on Al-Fe intermetallic phases having less than 10nm in size were observed to be distributed uniformly within the microstructure. The lattice parameter of matrix phase was estimated to be 0.4051nm. From this investigation, we could produce ultra-high strength Al alloy with yield strength of 768MPa at room temperature. Details would be discussed in correlation with microstructure and phase analysis result.