高温自蔓延过程中的挤压工艺对合成Ni_3Al-B-Cr合金的组织及力学性能的影响(英文)

Abstract

采用高温自蔓延及挤压工艺制备Ni3Al-0.5B-5Cr合金,研究挤压工艺对合成合金的微观组织及力学性能的影响。结果表明:合成后的挤压工艺可使合成合金进一步致密并能有效地细化其组织。X射线衍射及透射电镜观察发现除了Ni3Al基体外,合金中还含有Al2O3、Ni3B及Cr3Ni2析出相。与无挤压合成的合金有所不同,合金在高温自蔓延合成及挤压过程中经历了大变形和再结晶过程,其促进了组织的细化并降低了晶粒的取向差。此外,合成后的挤压工艺促使Al2O3颗粒重新分布且减少了γ-Ni相。与无挤压合成的合金相比,高温自蔓延合成及挤压工艺制备的合金具有更好的室温力学性能。

The well-densified Ni3Al-0.5B-5Cr alloy was fabricated by self-propagation high-temperature synthesis and extrusion technique. Microstructure examination shows that the synthesized alloy has fine microstructure and contains Ni3Al, Al2O3, Ni3B and Cr3Ni2 phases. Moreover, the self-propagation high-temperature synthesis and extrusion lead to great deformation and recrystallization in the alloy, which helps to refine the microstructure and weaken the misorientation. In addition, the subsequent extrusion procedure redistributes the Al2O3 particles and eliminates the gamma-Ni phase. Compared with the alloy synthesized without extrusion, the Ni3Al-0.5B-5Cr alloy fabricated by self-propagation high-temperature synthesis and extrusion has better room temperature mechanical properties, which should be ascribed to the microstructure evolution.