激光熔覆成形钨镍合金的组织与性能研究

摘要W-Ni 合金强度高、耐磨性好、热膨胀系数小、抗氧化性能好，是一种耐高温的难熔合金，是目前重要的难熔材料之一，被广泛应用于电子、机械、航天和军事工业等领域。本文通过激光熔覆成形这一新工艺来制备 W-Ni 合金，通过观察不同配比的 W-Ni 合金的组织与性能来确定最佳 W-Ni 质量分数，并在此基础上通过加入 Fe、Co 元素来提高 W-Ni 合金的强度和塑性。利用 XRD、SEM 、EBSD 等方法观察 W-Ni 合金的组织结构、相组成及内部枝晶生长情况，同时测量计算其相对致密度和显微硬度，与传统液相烧结工艺制备的 W-Ni 合金进行对比，并分析了相关作用机制。最后对含不同 Fe、Co 元素的拉伸试样进行了拉伸试验，观察其拉伸断口的形貌变化情况。实验结果表明：W-20wt。%Ni 是最佳的 W-Ni 配比，内部枝晶在熔覆层底部沿着近似平行于激光沉积方向生长，而在熔覆层顶部沿着平行于激光扫描方向生长。加入 Fe、Co 元素均能显著提高 W-Ni 合金的拉伸强度，与 Fe 元素相比，Co 元素更能改善 W-Ni 合金的塑性。从断口形貌上看加入 Fe、 Co 元素均使得断口表面韧窝明显增加。73788

毕业论文关键词激光熔覆成形 W-Ni 合金断裂机制枝晶生长相组成

毕业设计说明书外文摘要

Title Study on microstructure and properties of W-Ni alloy formed by laser cladding

Abstract W-Ni alloy has high strength, good wear resistance, low thermal expansion coefficient and good oxidation resistance。 It is a kind of refractory alloy, which is one of the most important refractory materials。 It is widely used in the fields of electronic, mechanical, aerospace and military industry。 In this paper, W-Ni alloy was prepared by laser cladding forming process。 The best W-Ni mass fraction was determined by observing the microstructure and properties of W-Ni alloy with different proportions。 The strength and plasticity of W-Ni alloy were improved by the addition of Fe and Co elements。 The microstructure, phase composition and internal dendrite growth of W-Ni alloy were observed by XRD,SEM,EBSD。Compared with the traditional W-Ni alloy prepared by liquid phase sintering process, the related mechanism was analyzed。 Finally, the tensile test specimens with different Fe and Co elements were carried out to observe the changes of the morphology of the tensile fracture surface。 The experimental results show that W-20wt。%Ni is the best W-Ni ratio。 The internal dendrite grows at the bottom of the cladding layer along the deposition direction, while the top of the cladding layer grows along the scanning direction。 The addition of Co has little effect on the W-Ni alloy, and the addition of Fe element can increase the tensile fracture toughness。

Keywords Laser cladding forming W-Ni alloy fracture mechanism dendrite growth phase composition

本科毕业设计说明书第 I 页

1 引言 1

1。1 W-Ni 合金 1

1。1。1 W-Ni 合金的性能与应用 1

1。1。2 W-Ni 合金的传统制备方法激光熔覆成形钨镍合金的组织与性能研究:http://www.youerw.com/cailiao/lunwen_83487.html