基于选择性相溶解的内生增强镁基非晶复合材料实验工艺设计

Experiment process design of in-situ reinforced Mg-based amorphous matrix composite via selective phase leaching method

针对材料成形实验教学中内生增强复合材料的制备工艺设计困难问题,该文以具备较好非晶形成能力的Mg_(65)Cu_(7.5)Ni_(7.5)Zn_(5)Ag_(5)Y_(10)(at.%)为基体,基于选择性相溶解法在非晶基体中成功引入原位自生B2-NiTi相。利用电弧熔炼制备Ni-Ti-Cu-Y预合金,通过成分设计使其析出B2-NiTi相,再将上述预合金浸入剩余元素(Mg,Zn,Ag)组成的熔体中。预合金中除B2-NiTi相以外的其他组成相会选择性溶解进入熔体中,组成Mg-Cu-Ni-Zn-Ag-Y熔体,B2-NiTi相分布其中。通过预先成分配比设计,使熔体成分与目标成分接近,具备较好的非晶形成能力。通过快速冷却制备得到原位自生B2-NiTi相增强镁基非晶复合材料。B2-NiTi形状记忆相在应力加载时会发生马氏体相变吸收能量,并阻碍主剪切带快速扩展,提高复合材料室温强韧性。复合材料断裂强度超过1 GPa,断裂应变为5.6%,屈服强度为730 MPa,塑性应变为4.6%,综合力学性能优于所选用的非晶基体合金。该工艺可适用于多种内生增强复合材料制备,为材料设计及组织性能表征实验教学提供了很好的范例。

To solve the difficulty in designing the fabrication process of in-situ metal matrix composites in materials and forming experimental teaching,this study selects a Mg_(65)Cu_(7.5)Ni_(7.5)Zn_(5)Ag_(5)Y_(10)(at.%)amorphous alloys as amorphous matrix for its good amorphous forming ability.The in-situ B2-NiTi phase has been successfully induced among the matrix via selective phase leaching method.Ni-Ti-Cu-Y precursor is fabricated by arc-melting,in-situ B2-NiTi phase precipitated with proper composition design.By immersing the precursor in Mg-Zn-Ag melt,the phases in precursor selectively dissolved into the melt except B2-NiTi phase,to form an amorphous-formable Mg-Cu-Ni-Zn-Ag-Y melt with the same composition in target amorphous matrix.The in-situ B2-NiTi reinforced Mg-based amorphous matrix composites are prepared by rapid quenching the semi-solid liquid.The stress-induced martensitic transformation could occur in B2-NiTi shape-memory phase during deformation,which contributes to the hindering effect on the rapid propagation of main shear bands and improves the room-temperature plasticity of the composites.The fracture strength of the composites exceed 1 GPa,and the fracture strain is about 5.6%.The yielding strength is about 730 MPa,the plastic strain is 4.6%,which is far more better than the chosen amorphous base alloys.The present process can be used in fabrication of various in-situ metal matrix composites and contributes to the development of materials design and characterization experimental teaching.