Microstructures of Fe-C system hard alloys produced from mechanically alloyed powders

Yuuji Kimura, Setsuo Takaki, Hideto Goto

    Research output: Contribution to journalArticlepeer-review


    Fe-C system hard alloys were produced from mechanically alloyed powders and their properties were examined by means of hardness testing and microstructural examinations. Mixtures of iron and graphite powders(Fe-2-6mass%C) were mechanically alloyed with vibration-ball-mill in Ar atmosphere. MA powders obtained were packed in stainless steel tubes and then sealed in vacuum after degassing at 873K. The stainless steel tubes were hot-rolled in the temperature range of 923K-1273K to consolidate MA powders. Bulk materials were subjected to isothermal annealing at 1273K, followed by water quenching. After the ball-milling of 360ks, extremely large deformation energy was stored within powder particles. This leads to the formation of ultra-fine α-Fe grain and very fine dispersion of graphite. On heating to a consolidation temperature, the reaction forming Fe3C takes place at around 600K. MA powders were completely densified to full density by hot-rolling at 1123K where the structure is of (Fe3C+γ Fe) two-phase, and this consolidation process does not accompany significant coarsening of the microstructure. In a case of an Fe-6mass%C MA bulk material, the structure at room temperature is composed of 80vol% Fe3C and 20vol%α-Fe, so that hardness of a bulk material reaches to Hv900. But, Fe3C is not so stable at elevated temperatures that it easily decomposes to Fe and graphite after long annealing.

    Original languageEnglish
    Pages (from-to)584-589
    Number of pages6
    JournalFuntai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy
    Issue number5
    Publication statusPublished - 1996

    All Science Journal Classification (ASJC) codes

    • Mechanical Engineering
    • Industrial and Manufacturing Engineering
    • Metals and Alloys
    • Materials Chemistry


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