电弧熔炼Ti6Al4V/B_(4)C复合材料微观组织与力学性能

Microstructure and mechanical properties of Ti6Al4V/B_(4)C composite prepared by arc melting

采用真空电弧熔炼技术制备了不同含量B_(4)C的Ti6Al4V/B_(4)C钛基复合材料,并采用光学显微镜、扫描电子显微镜、显微硬度计、静态压缩及拉伸测试等对其微观组织及力学性能进行了表征分析。结果表明,电弧熔炼过程B_(4)C与钛基体原位反应生成TiB,TiC及TiB_(2)相,TiB呈现一维生长晶须状,TiC呈现颗粒状,在B_(4)C质量分数为10%时生成块状TiB_(2),并可能会形成特殊的中空棱柱状结构Ti(B_(x)C_(y))聚合物。原位反应生成的TiB_(2)可显著提高钛基复合材料的显微硬度。当B_(4)C质量分数为0.5%时,钛基复合材料原位反应生成的连续网状、均匀分布的TiB和TiC试样具有最优力学性能,试样最大抗压强度值达到1990 MPa,最大压缩应变为35.5%,压缩性能超过熔炼钛合金,抗拉强度达到1034 MPa,与熔炼钛合金材料相比提高近24%,但塑性有所降低,并随着B_(4)C含量增加,抗拉强度逐渐下降,其断裂方式由韧性断裂转变为脆性断裂。

Ti6Al4V/B_(4)C titanium matrix composites with different B_(4)C contents were prepared by vacuum arc melting.The microstructure and mechanical properties were characterized and analyzed by optical microscope,scanning electron microscope,microhardness tester,static compression and tensile test.The results show that in the process of arc melting,B_(4)C reacts with titanium matrix in situ to form TiB,TIC and TiB_(2)phases.TiB presents one-dimensional long whisker shape,TiC presents granular shape,and massive TiB_(2)is formed when the content of B_(4)C is 10 wt.%,and a special hollow prismatic Ti(B_(x)C_(y))polymer may be formed.TiB_(2)produced by in-situ reaction significantly improve the microhardness of titanium matrix composites.When the content of B_(4)C is 0.5 wt.%,the continuous network and evenly distributed structure of TiB and TiC produced by the in-situ reaction of titanium matrix composites has the best mechanical properties.The maximum compressive strength of the sample reaches 1990 MPa and the maximum compressive strain is 35.5%.The compressive property exceeds that of molten titanium alloy.The tensile strength reaches 1034 MPa,which is nearly 24%higher than that of molten titanium alloy,but the plasticity decreases.With the increase of B_(4)C content,the tensile strength decreases gradually,titanium matrix composites gradually change from ductile fracture to brittle fracture.