Cu–(Fe–C)合金中Fe–C相的固态转变对其摩擦磨损行为及机理的影响

Effect of the solid-state transition of Fe–C phase on the friction and wear behavior and mechanism of Cu–(Fe–C) alloys

  • 摘要: 采用光学显微镜(OM)、扫描电子显微镜(SEM)、纳米力学探针、力学性能测试以及室温摩擦磨损实验研究了Cu–(Fe–C)合金的铸态组织、形变态组织、Fe–C相形貌、力学性能和摩擦磨损行为。结果表明,Cu–(Fe–C)合金中弥散分布着微米级和纳米级的Fe–C相,其中微米级的Fe–C相在淬火和回火过程中发生了固态转变,这种固态转变与钢中的马氏体转变和回火转变类似。合金先在850 ℃淬火,然后在200、400和650 ℃回火,Fe–C相由针状马氏体逐渐向颗粒状回火索氏体转变,Fe–C相纳米硬度分别为9.4、8、4.2和3.8 GPa,实现了对强化相硬度的控制。室温摩擦磨损实验结果表明,随着回火温度升高,合金的磨损机制逐渐由犁削向黏着磨损和大塑性变形转变,导致合金的耐磨损性能降低。这一结论可以为通过Fe–C相的固态转变的方法调控Cu–(Fe–C)合金的摩擦磨损性能提供参考作用。

     

    Abstract: The effect of solid-state phase transformation during heat treatment on the friction and wear properties of Cu–3Fe–0.18C alloy prepared by vacuum melting was studied. The as-cast structure, deformed structure, Fe–C phase morphology, mechanical properties, and the friction and wear behavior of Cu–Fe–C alloy were studied by optical microscopy (OM), scanning electron microscopy (SEM), nano-mechanical probe analysis, mechanical properties test, and friction and wear experiments, respectively, at room temperature. The results show that micro- and nano-sized Fe–C phases are dispersed in the Cu–(Fe–C) alloy, and the micron-sized Fe–C phase undergoes solid-state transformation during quenching and tempering, which is similar to the martensite transformation and tempering transformation in steel. After quenched at 850 ℃ and tempering at 200, 400 and 650 ℃, the Fe–C phase gradually transforms from acicular martensite to granular tempered sorbite. The corresponding nano-hardness of the Fe–C phase is 9.4, 8, 4.2 and 3.8 GPa, respectively, and the hardness of the strengthening phase is controlled. Through an analysis of tensile fracture, a large number of dissociation surfaces appear on the fracture surface of the quenched alloy. The crack source is located at the interface between the Fe–C phase and the matrix. With an increase in the tempering temperature, the dissociation surface of the fracture surface of the tempered alloy gradually decreases until it disappears, and the crack source gradually transfers to the matrix. The evolution of fracture surface indicates that the bonding between Fe–C phase and matrix in the quenched alloys is poor. With the increase of the tempering temperature, the bonding interface between the Fe–C phase and the matrix is improved. The experimental results of friction and wear at room temperature show that with the increase of tempering temperature, the wear mechanism of the alloy gradually changes from ploughing to adhesion wear and severe plastic deformation, which results in a decrease in the alloy wear resistance. This paper can provide a reference for controlling the friction and wear properties of Cu–(Fe–C) alloys by the solid-state transformation of the Fe-C phase martensitic decomposition.

     

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