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系统总结了面心立方(fcc)金属材料在等通道转角挤压(ECAP)变形后的晶粒细化、微观结构演化规律和力学性能.根据ECAP变形的特点,利用具有特殊取向的Al单晶体和Cu双晶体,经过一道次ECAP挤压发现:材料在ECAP模具对角面附近发生严重塑性变形;除了沿模具对角面切应力的作用外,沿垂直于模具对角面的切应力也起重要作用.此外,通过设计特殊取向的Cu单晶体、Al单晶体和粗晶Cu-3%Si合金经过一道次ECAP挤压,系统研究了层错能、晶粒尺寸和晶体学取向对fcc金属形变孪生所需的孪生应力的影响.对具有不同层错能的Cu-Al合金进行多道次ECAP挤压表明,随着层错能降低,Cu-Al合金的晶粒细化机制逐步从位错分割机制转变为孪生碎化机制,最小晶粒尺寸逐步减小,具有较高或较低层错能材料比中等层错能材料更容易获得均匀的微观组织;Cu-Al合金的拉伸强度和均匀延伸率随着层错能的降低同步提高,即随着层错能的降低,Cu-Al合金的强度-塑性匹配性提高.
The grain refinement, microstructure evolution and mechanical properties of face-centered cubic (fcc) metal after ECAP deformation were systematically summarized.According to the characteristics of ECAP deformation, Cu double crystals. After one pass of ECAP extrusion, the material was found to undergo severe plastic deformation near the diagonal of the ECAP mold. In addition to shear stress along the diagonal of the mold, shear stress perpendicular to the diagonal of the mold also played an important role In addition, through the design of a special orientation of Cu single crystal, Al single crystal and coarse grain Cu-3% Si alloy through a ECAP extrusion, the system studied the stacking fault energy, grain size and crystallographic orientation of the fcc metal deformation twin The effect of the twin stress required on the Cu-Al alloy with multi-pass ECAP extrusion shows that the grain refinement mechanism of the Cu-Al alloy gradually increases from the dislocation partitioning mechanism To the twinning mechanism, the minimum grain size is gradually reduced, and the higher or lower layers of the faulty material are easier to obtain uniform microstructure than the medium layer of mis-energy materials. The tensile strength and uniform elongation of the Cu-Al alloy Rate with layer fault can Decreases with the decrease of the stacking error, that is, the strength-plastic matching of the Cu-Al alloy increases with the decrease of the stacking fault energy.