针对传统 γ-TiAl合金室温塑性低、难以满足工程化应用的难题,本文提出Nb相增塑核壳结构TiAl/Nb复合材料,系统研究了复合材料的制备工艺和力学性能。结果表明：在200 r/min转速下球磨120 h可实现细小Nb颗粒对大尺寸 γ-TiAl雾化粉的完全包裹,随后在40 MPa下,1 200 ℃真空热压1 h可获得增塑相可控的致密核壳结构组织。制备的TiAl/Nb复合材料在室温下的屈服强度为971.5 MPa,抗压强度为2 337.7 MPa,断裂应变为31.7%,表现出高强度和良好的塑性。这种强度和塑性的协同提高归因于延性β-Nb相促进了基体相之间的协调变形,提高了材料的整体持续变形能力。
In response to the challenges of the low plasticity at room temperature and difficulty in meeting engineering applications in traditional γ-TiAl alloys, this paper proposed Nb phase plasticized TiAl/Nb composites with core-shell structure, and systematically studied the preparation technology and mechanical properities of the composites. The results show that complete encapsulation of large-sized γ-TiAl atomized powder by fine Nb particle can be achieved after 120 h ball milling at the speed of 200 r/min. Subsequently, a densified core-shell structure with controllable plasticized phase can be obtained after vacuum hot pressing at 1 200 ℃/1 h, under 40 MPa. The prepared TiAl/Nb composites exhibit high strength and good plasticity with the yield strength of 971.5 MPa, compressive strength of 2 337.7 MPa, and fracture strain of 31.7% at room temperature. The high strength and excellent plasticity of the composites are attributed to the ductile β-Nb phase which facilitates coordinated deformation between matrix phase colonies, which thereby enhancing the continuous deformation capacity of the integral bulk materials.
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