内生枝晶相体积分数可控的钛基非晶复合材料

Ti-BASED AMORPHOUS COMPOSITES WITH QUANTITATIVELY CONTROLLED IN-SITU FORMATION OF DENDRITES

采用直接调控增塑相摩尔分数的方法成功制备了系列含有bcc枝晶相的(Ti32.8zr30.2Ni5 3Cu9Be22 7)100-s(Ti61 5-Zr36 4Cu2.1)x(x=10—95)非晶复合材料.采用xRD,SEM和DSC等方法研究了不同x值下枝晶相的体积分数以及形貌的变化规律,并利用TEM研究了内生枝晶相的结构和两相界面结构.结果表明,在Ti32 8Zr30 2Ni5 3Cu9Be22 7合金中直接添加不同量的Ti61 5Zr36.4Cu2.1合金能够有效地控制内生枝晶相的析出量,获得界面结合良好的非晶复合材料,且枝晶相的尺寸及体积分数与x值成正比.室温压缩实验结果表明,当x>30时,复合材料的塑性变形能力可得到明显改善.x值越大,枝晶相体积分数越高,复合材料屈服强度越低,塑性改善效果越明显.不同体积分数的复合材料均表现出明显的加工硬化现象.当x=90时,复合材料的塑性变形量达到14.4%,断裂极限强度达1917 MPa.

A series of （Ti32.sZr30.2Nis.3CugBe22.7）100-x （Ti61.5Zr36.4Cu2.1）x （x=10--95） bulk amorphous composites with quantitatively controlled in-situ formation of bcc-dendrites were prepared. The microstructures were analyzed by SEM, XRD and TEM. Thermal behaviors were examined using DSC. The results show that the size and volume fraction of dendrites depend on x in the composites. With increasing x, the volume fraction of dendrites rises monotonically from 20% to 90%. The microstructural transition between the matrix and the dendrites is smooth and successive with no phases observed at the interface. Compression tests show the size and volume fraction of dendrites largely influence the mechanical properties of composites. When the volume fraction is larger than the critical value （approximately 30% in the present work）, the plasticity of composites cannot be improved. When the volume fraction is over the critical value, the higher the volume fraction of dendrites, the larger the plastic strain, the stronger the work hardening capacity. It implies that the properties of composite can be mediated by the tunable volume fraction of dendrites. These findings are significant to develop the controllable microstructure and performance materials. When x=90, the plastic strain and the compressive strength of the composites reach 14.4% and 1917 MPa, respectively.