超大塑性变形的研究进展一块体纳米材料性能(3)

Review and Prospect of Severe Plastic Deformation——Properties of Bulk Nanometer Crystalline Materials(3)

超大塑性变形制备的纳米材料通常具有高强度、低塑性的特点,低塑性主要是由于纳米材料的应变硬化能力较低造成的,但可以通过随后的退火来改善;纳米材料的双峰结构的制备是获得较好强、塑性配合的一种途径;纳米材料可以在较低温度、较高应变速率下实现超塑性,提高高周疲劳寿命;细小的第二相粒子析出是提高纳米材料热稳定性的关键。与常规冷轧材料相比,超大塑性变形制备的材料在相同强度下的塑性较高。

Nanometer crystalline material produced by SPD behaves high strength and low plasticity, low plasticity is mainly caused by its lower strain - hardening ability, and can be improved by following annealing. The achievement of bimodal microstructure of nanometer crystalline material is one of the method to obtain better combination of high strength and high plasticity. Nanometer crystalline material can get the super- plasticity at lower temperature or higher strain rate, and its high cycle fatigue life can be raised. The fine second phase precipitation is the key to improve the heat stability of NC - materials. Having same strength, the materials produced by SPD behave higher plasticity than that by conventional rolling.