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电弧熔炼Ti6Al4V/B4C复合材料微观组织与力学性能

Microstructure and mechanical properties of Ti6Al4V/B4C composite prepared by arc melting

  • 摘要: 采用真空电弧熔炼技术制备了不同含量B4C的Ti6Al4V/B4C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B4C与钛基体原位反应生成TiB,TiC及TiB2相,TiB呈现一维生长晶须状,TiC呈现颗粒状,在B4C质量分数为10%时生成块状TiB2,并可能会形成特殊的中空棱柱状结构Ti(BxCy)聚合物. 原位反应生成的TiB2可显著提高钛基复合材料的显微硬度. 当B4C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1 990 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1 034 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B4C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.

     

    Abstract: Ti6Al4V/B4C titanium matrix composites with different B4C 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, B4C reacts with titanium matrix in situ to form TiB, TIC and TiB2 phases. TiB presents one-dimensional long whisker shape, TiC presents granular shape, and massive TiB2 is formed when the content of B4C is 10 wt.%, and a special hollow prismatic Ti (BxCy) polymer may be formed. TiB2 produced by in-situ reaction significantly improve the microhardness of titanium matrix composites. When the content of B4C 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 1 990 MPa and the maximum compressive strain is 35.5%. The compressive property exceeds that of molten titanium alloy. The tensile strength reaches 1 034 MPa, which is nearly 24% higher than that of molten titanium alloy, but the plasticity decreases. With the increase of B4C content, the tensile strength decreases gradually, titanium matrix composites gradually change from ductile fracture to brittle fracture.

     

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