Ti/TiAl复合板大压下率热轧复合行为及组织性能研究

Study on Hot Rolling Bonding Behavior and Microstructure and Properties of Ti/TiAl Clad Plate under Large Reduction

摘要:

采用大压下率包套热轧法成功制备了界面无缺陷的Ti-6Al-4V(wt.%)/Ti-43Al-3V-2Cr(at.%)复合板，并对复合板的显微组织和力学性能进行了研究。实验结果表明，观察到界面区域无明显缺陷，成功避免了Kirkendall现象。复合板界面厚度约为230 μm，根据相组成不同，将界面分为两个区域，其中1区域为近Ti6Al4V合金界面处，主要由α/α2+β/B2相组成；界面2区域为近TiAl合金界面处，主要为α/α2+β/B2+γ相。界面区域结构是由于Ti6Al4V合金中Ti元素扩散到TiAl合金层以及由TiAl层的Al和Cr元素扩散到Ti6Al4V合金层所致。测试了复合板的维氏硬度和不同加载方式的三点抗弯强度。实验结果表明，界面1处具有最高的显微硬度，横向试件表面加载时复合板表现出最佳的抗弯能力，抗弯强度达到1150.82 MPa，并结合显微组织特征对其力学性能进行了详细分析和讨论。

Abstract:

Ti-6Al-4V(wt.%)/Ti-43Al-3V-2Cr(at.%) composite plates with no interfacial defects were successfully prepared by a high-reduction hot-rolling method. Microstructure and mechanical properties were studied. The experimental results show that no obvious defects in the interfacial region are observed, and the Kirkendall phenomenon is successfully avoided. The interface thickness of the composite plate is about 230 μm, according to different phase compositions, the interface is divided into two regions, one of which is near the interface of Ti6Al4V alloy and is mainly composed of α/α2 + β/B2 phase; Interface 2 is near the interface of TiAl alloy, and mainly consists of α/α2 + β/B2 + γ phase. The interface region structure is due to the diffusion of Ti element in Ti6Al4V alloy to TiAl alloy layer and the diffusion of Al and Cr elements from TiAl layer to Ti6Al4V alloy layer. The Vickers hardness and three-point flexural strength of the composite panels were tested with different loading methods. The experimental results show that the interface 1 has the highest microhardness, and the composite plate exhibits the best bending resistance when the surface of the transverse specimen is loaded, and the bending strength reaches 1150.82 MPa. The mechanical properties were analyzed and discussed in detail in combination with the microstructure characteristics.