We reported the fracture behavior of multimodal AA7075-B₄C composites with three types of coarse grains (CG, AA7075 powder-1 μm, AA7075 powder-10 μm, and as-cryomilled AA7075 powder) synthesized via cryomilling and plasma activated sintering. Our results indicated that the type (particle size) and weight fraction could affect the distribution of CGs, which in turn significantly affect the fracture behavior of multi-modal composites. Multiple voids were found in the vicinity of AA7075 powder-1 μm, leading to a limited plasticity even with a lower yield strength. AA7075 powder-10 μm (25%) could distribute homogeneously in the composites, resulting in a high yield strength (712 ± 24 MPa) with the plasticity of ~7.7%. The localized grain growth occurred during consolidation with addition of as-cryomilled AA7075 powder. Noted that once the continuous distribution of CGs were detected in the composites, the yield strength decrease dramatically. The CGs could enhance the plasticity by retarding the propagation of micro-cracks during deformation.

我们报告了多模态 AA7075-B ₄的断裂行为通过低温研磨和等离子体活化烧结合成的具有三种粗晶粒（CG、AA7075 粉末-1 μm、AA7075 粉末-10 μm 和低温研磨的 AA7075 粉末）的 C 复合材料。我们的结果表明，类型（粒度）和重量分数会影响 CG 的分布，进而显着影响多模态复合材料的断裂行为。在 AA7075 粉末 1 μm 附近发现了多个空隙，即使屈服强度较低，也导致塑性有限。AA7075 粉末-10 μm (25%) 可以在复合材料中均匀分布，产生高屈服强度 (712 ± 24 MPa) 和~7.7% 的塑性。在加入低温研磨的 AA7075 粉末的固结过程中发生局部晶粒生长。注意到一旦在复合材料中检测到连续分布的 CG，屈服强度急剧下降。CGs 可以通过在变形过程中延缓微裂纹的传播来提高塑性。