利用鈦基焊料接合氧化鋯與鈦合金之介面微觀結構及其反應機構

Abstract

本研究分別使用兩種焊料Ti-15Cu-25Ni及Ti-37.5Zr-15Cu-10Ni接合Ti-6Al- 4V及3YSZ，在氬氣保護氣氛中，接合條件為溫度920°C分別持溫6 min、30 min、60 min，利用SEM/EDS對接合後試片做介面微觀結構分析，探討兩種焊料及時間變化對接合的差異性。以Ti-15Cu-25Ni焊料接合在920°C/6 min條件下，鈦側生成α-Ti/Ti2(Ni, Cu)的共析層狀結構層，焊料基底生成Ti2(Ni, Cu)，並析出α-Ti及TiNi(Cu)，氧化鋯側反應生成TixOy。當持溫時間變長時，因原子持續擴散使鈦側的α-Ti/Ti2(Ni, Cu)層與氧化鋯側的TixOy層變厚，焊料中的Ti朝氧化鋯側擴散使TiNi(Cu)減少，而焊料內成分趨向均質化，使焊料基底生成較均質的Ti2(Ni, Cu)；持溫60 min時，焊料內部原子擴散趨向平衡，焊料均質化，在高溫凝固成固體，液相消失。以Ti-37.5Zr-15Cu-10Ni焊料接合在920°C/6 min條件下，鈦側生成α-Ti/β’-Ti/ (Ti, Zr)2(Ni, Cu)的層狀結構層，焊料生成不同成分比的(Ti, Zr)2(Ni, Cu)及α-Ti，氧化鋯側生成以TixOy為主的兩層反應層。持溫時間變長時，原子持續擴散，使鈦側的層狀結構層變厚，因Zr持續朝鈦側擴散，焊料中Ti-rich的(Ti, Zr)2(Ni, Cu)變多，氧化鋯側的TixOy層變厚；持溫60 min時，因Zr持續朝鈦側擴散，焊料內部Zr含量減少，使焊料熔點上升，焊料在高溫時凝固成固體，液相消失。

In this study, the joining of Ti-6Al-4V and 3YSZ was brazed by Ti-15Cu-25Ni or Ti-37.5Zr-15Cu-10Ni amorphous fillers at 920°C for various periods in the atmosphere of argon. The microstructure of the joints were characterized by SEM/EDS. With Ti-15Cu-25Ni after brazing 6 min, α-Ti/Ti2(Ni, Cu) lamellar structure was formed in the Ti-6Al-4V side. In the filler, Ti2(Ni, Cu) was formed as the substrate, while α-Ti and TiNi(Cu) were precipitated. TixOy was formed in the 3YSZ side. For longer holding time, the α-Ti/Ti2(Ni, Cu) layer and TixOy layer would become thicker. For brazing 60 min, because the filler became homogeneous, the liquid phase was disappered. With Ti-37.5Zr-15Cu-10Ni after brazing 6 min, α-Ti/β’-Ti/(Ti, Zr)2(Ni, Cu) lamellar structure was formed in the Ti-6Al-4V side, while different composition ratios of (Ti, Zr)2(Ni, Cu) and α-Ti were formed in the filler. TixOy was formed in the 3YSZ side. For longer holding time, the thickness of α-Ti/β’-Ti/(Ti, Zr)2(Ni, Cu) lamellar layer and TixOy layer would be thicker because of the diffusion of atoms. For brazing 60 min, because Zr atoms were diffused into the Ti-6Al-4V side, the melting point of the filler became higher. The liquid phase in the filler was disappeared.