鈮與鋯金屬真空硬銲之研究

Abstract

為了評估 Nb 及 Zircaloy-2 接合的特性，分別使用 Ti-35Ni-15Nb 及 Ti-25Ni-15Nb 做為硬銲填料，在不同溫度及時間進行真空硬銲，將 Nb 與 Nb 及Zircaloy-2 與 Zircaloy-2 分別接合。 於 Nb/Ti-35Ni-15Nb/Nb 的實驗中，銲道組織主要是由 Ti2Ni 及 TiNi 介金屬化合物與球狀的 (β-Ti,Nb) 固溶體所組成。自 BEI 的分析中可以得知，裂縫主要由黑色的 Ti2Ni 介金屬化合物生成及成長。銲道強度因 Ti2Ni 介金屬化合物的生成而降低。然而，提高硬銲溫度可以降低 Ti2Ni 介金屬化合物的生成量，進而使得銲道生成大量的球狀 (β-Ti,Nb) 固溶體。實驗結果顯示，使用Ti-35Ni-15Nb 填料可被應用在 Nb 與 Nb 的接合。 使用 Ti-25Ni-15Nb 接合 Zircaloy-2 與 Zircaloy-2 ，可以發現硬銲溫度越高及硬銲時間越長，網狀銲道組織越發達。在 900 oC 時，銲道組織中可發現有黑色的 Zr2Ni 及 ZrTiNi 生成。當溫度提升至 1200 oC時，銲道組織主要為網狀組織，其銲道剪力強度可達到 365 MPa。

To evaluate niobium and zircaloy-2 joints characteristics, vacuum brazing niobium using Ti-35Ni-15Nb foil and zircaloy-2 using Ti-25Ni-15Nb foil in different brazing temperature and brazing time were performed. In vacuum brazing niobium experiment, the joint consists of Ti2Ni, TiNi intermetallic compounds and globular (β-Ti,Nb) particles. From SEM backscattered electron image analyse, cracks primarily initiated and grown along the black Ti2Ni intermetallic compound of the joint. The black Ti2Ni intermetallic compound would decay the shear strength of the joint. However, increasing brazing temperature would decrease the amounts of the Ti2Ni intermetallic compound, and form many globular (β-Ti,Nb) particles. Ti-35Ni-15Nb filler is a good candidate and shows potential in brazing niobium. In the vacuum brazing zircaloy-2 using Ti-25Ni-15Nb study, increasing the brazing temperature and brazing time, the basketweave structure formed much apparently. Some long-rod structures and small black particles mixed and spread in the basketweave structure. When the joint brazed at 900 degrees centigrade, joint is comprised of black Zr2Ni and ZrTiNi intermetallic compounds. At 1200 degrees centigrade, the basketweave structure was the main structure of the joint. When the experiment performed at 1200 degrees centigrade for 60 minutes, the average shear strength of joint is increased to 365 MPa.