热变形方式对2D70耐热铝合金组织与性能的影响

分别采用常规变形方式(直接挤压)、强变形方式(3次多方锻造与挤压变形相结合)制备了大规格2D70耐热铝合金棒材,利用金相显微镜、透射电镜、力学性能测试、电导率测试等手段对比分析了两种工艺所获得棒材的变形态、固溶态显微组织特征以及195℃人工时效强化特性差异。结果表明,与传统直接挤压方式相比,采用强变形工艺所获得的基体组织相对均匀,合金中各类第二相破碎严重、分布合理;经强变形破碎的Al2CuMg、Al2Cu等可溶第二相可在固溶处理过程中充分回溶以提高时效强化潜力,同时,Al9FeNi、Al7Cu4Ni等难溶第二相的尺寸、形态与分布通过强变形得以合理调控,使得合金棒材在195℃人工时效的过时效阶段具有更优越的抗过时效能力,合金热稳定性较好。

Influence of Thermal Deformation Routes on Microstructure and Mechanical Properties of 2D70 Heat Resistant Aluminum Alloy

The large scale rods of a heat-resistant 2D70 aluminum alloy were fabricated by conventional defor-mation(extruding) and intensive deformation(forging and extruding) routes.The influence of thermal deformation routes on as-deformed and as-quenched microstructure and aging characteristics were investigated by means of optical microscopy(OM),scanning electron microscopy(SEM),transmission electron microscopy(TEM),mechanical pro-perties and electrical conductivity measurements.The results show that the grains become more homogeneous and the secondary phases are crushed adequately by intensive deformation.After intensive deformation,the soluble Al2CuMg,Al2Cu phases can be dissolved adequately into the matrix during solid solution treatment,leading to promote the aging strengthening potential.Meanwhile,the size,morphology and distribution of insoluble Al9FeNi,Al7Cu4Ni phases have been controlled reasonably through intensive deformation,which can improve the resistance of over-aging under the aging temperature of 195℃.Compared with the conventional deformation route,better thermal stability can be obtained by intensive deformation.