热等静压Cr3 C2/Ni3 Al复合材料的微观组织及相组成

采用热等静压技术(HIP)在1160℃、100 MPa 条件下制备出 Cr3 C2/Ni3 Al 复合材料,研究了 Cr3 C2/Ni3 Al复合材料的微观组织和相组成。结果表明,Cr3 C2初始颗粒首先溶解成 Cr 和 C 原子,并往基体中扩散；冷却过程中,溶解的Cr和C原子转化为稳定的Cr7 C3结构；由于 Ni3 Al合金中的 Fe易与 C形成稳定碳化物,促使Fe原子从基体中往Cr7 C3结构中发生上坡扩散,并取代Cr7 C3结构中的部分Cr原子形成 M7 C3(M为 Cr、Fe,余同)结构的扩散相。当Cr3 C2初始颗粒较大时,在高温过程中,Cr3 C2颗粒未能全部溶解,而未溶解的 Cr3 C2颗粒芯部在冷却过程中仍保持为Cr3 C2结构。该条件下制备的Cr3 C2/Ni3 Al复合材料主要由Cr3 C2硬芯相、M7 C3扩散相和γ′-Ni3 Al基材相组成,其中Cr3 C2硬芯相和γ′-Ni3 Al基材相通过M7 C3扩散相形成良好的扩散连接；该结构的复合材料磨损后表面Cr3 C2颗粒末发生剥落且沟槽在铬碳化物处发生中断,表现出良好的耐磨性。

Microstructure and phases constitution of Cr3 C2/Ni3 Al composites prepared by hot isostatic pressing (HIP)

The Cr3 C2/Ni3 Al composite materials were prepared by hot isostatic pressing (HIP)at 1 160℃ and 100 MPa. Microstructure and phases constitution of the composite materials were investigated.The results indicate that the original Cr3 C2 particle firstly dissolves into Cr and C atoms and then diffuses into the matrix.During the cooling process,the dissolved Cr and C atoms transformed into a stable Cr7 C3 structure.Also,an uphill diffusion phe-nomenon is observed for Fe element from the matrix to the Cr7 C3 carbide phase,which is attributed to the easy formation of stable carbides of Fe element in Ni3 Al alloy with C element.And,the Fe atoms substitute a part of Cr atoms in Cr7 C3 carbides and form a diffusion phase with M7 C3 (M for Cr,Fe)structure.When the original Cr3 C2 par-ticles are large,it cannot be completely dissolved during the high temperature period.The undissolved core of Cr3 C2 particles still remain the Cr3 C2 structure after the cooling process.The Cr3 C2/Ni3 Al composite materials are composed of Cr3 C2 hard core phase,M7 C3 diffusion phase andγ′-Ni3 Al matrix material phase.The Cr3 C2 hard core phase and theγ′-Ni3 Al matrix created a good diffusion bonding by the formed M7 C3 diffusion phase.There-fore,the Cr3 C2 particle on the worn surface does not peel off and the groove is interrupted around the chromium carbides during the wear test,resulting in significantly improved wear resistance of Cr3 C2/Ni3 Al composites.