摘要:
在NiTi合金中添加少量Al、Nb、Hf强化元素, 采用定向凝固原位自生法制备了一种NiTi基自生复合材料, 并在950 ℃对定向凝固棒分别进行了12 h、50 h及100 h的均匀化热处理, 对热处理后的试样进行了室温抗拉强度测试。结果表明, 定向凝固组织为沿[001]方向生长的细小的棒状胞晶组织, β-Nb相和Ti2Ni相增强体颗粒沿NiTi胞晶间的[001]方向排列。随热处理时间的延长, 胞晶尺寸逐渐粗化, 两增强相粒子分布更加弥散均匀。热处理后NiTi基自生复合材料的最大抗拉强度达到1972 MPa, 超过了4130和8640超高强度钢, 与4140和4340超高强度钢的强度基本相当, 达到或超过了多种国内外现役的超高强度钛合金。
Abstract:
NiTi metal matrix in-situ composite was prepared by directional solidification in-situ method, adding a small amount of Al, Nb, Hf. The directionally solidified bars were homogenized at 950 ℃ for 12 h, 50 h and 100 h, respectively, and the tensile strength was tested at room temperature. The results indicate that a vimineous, acicular cellular structure that grow along the [001] orientation is achieved after the directional solidification. The β-Nb and Ti2Ni reinforcement particles distribute along the [001] orientation in the intercellular regions. The cellular structure becomes coarser with the increase of the homogenizing time, and the two reinforcement particles are more dispersed and distributed more homogeneously. After heat treatment, the highest tensile strength reaches to 1972 MPa, exceeding that of the 4130 and 8640 ultrahigh-strength steel, being almost equal to 4140 and 4340 ultrahigh-strength steel, and reaching or surpassing many kinds of ultrahigh-strength titanium alloy.
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