Research on the properties of bulk cementite prepared by mechanical alloying

机械合金化制备大块渗碳体的性能研究

• 批准号: 12450281
• 负责人: UMEMOTO Minoru
• 金额: $ 9.15万
• 依托单位: Toyohashi University of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450281/
• 关键词: steel; cementite; mechanical alloying; sintering; strength; allying; mechanical properties; physical properties

Cementite is one of the most important phases in steels, which plays a critical role in mechanical properties of steels. As a basic phase in steels, the understanding of its mechanical, physical and chemical properties is particularly desired. It is claimed to be metastable at all temperatures with respect to graphite and its saturated solution in iron.The present research has led to successful fabrication of bulk cementite by mechanical alloying (MA) with subsequent spark plasma sintering (SPS). Bulk cementite with dimensions of up to 50 mm in diameter have been produced. The mechanical and physical properties of Fe_3C have been measured.It was found that the color of cementite is metallic like pure iron. Its hardness is about 10GPa which is 10 times higher than that of pure iron. The Young's modulus of cementite is 190GPa and 10% smaller than that of pure iron. The electrical resistivity of cementite is 100/μΩ・cm and about 10 times higher than that of pure iron.The influence of Cr, Mn, V, Mo, Ti, Ni and Si additions substitutional to Fe on the structure and properties of cementite bulk has also been studied. It has been found that Cr, Mn, V and Mo can form alloyed cementite and stabilize it while Ti, Ni and Si destabilize or even suppress the formation of cementite. The hardness and Young's modulus of cementite were increased by the addition of both Cr and Mn. Thermal expansion coefficient was increased substantially by Cr or Mn additions. Slight decrease in Cp was observed by the addition of Cr or Mn.

渗碳体是钢中最重要的相之一，对钢的力学性能起着至关重要的作用。作为钢的基本相，对其机械、物理和化学性质的了解是特别需要的。它在所有温度下对石墨及其在铁中的饱和溶液都是亚稳的。本研究成功地利用机械合金化（MA）和随后的放电等离子烧结（SPS）制备了块状渗碳体。已生产出直径可达50毫米的散装渗碳体。测定了Fe_3C的力学和物理性能。渗碳体的颜色与纯铁相似，呈金属色。其硬度约为10GPa，是纯铁的10倍。渗碳体的杨氏模量为190GPa，比纯铁的杨氏模量小10%。渗碳体的电阻率为100/μΩ·cm，比纯铁的电阻率高约10倍。研究了Cr、Mn、V、Mo、Ti、Ni和Si取代Fe对渗碳体结构和性能的影响。研究发现，Cr、Mn、V和Mo能够形成合金渗碳体并使其稳定，而Ti、Ni和Si则会使渗碳体失稳甚至抑制渗碳体的形成。Cr和Mn的加入均提高了渗碳体的硬度和杨氏模量。Cr或Mn的加入大大提高了热膨胀系数。加入Cr或Mn后，Cp略有下降。