紅外線硬銲接合鈦合金及高熵合金之研究

Abstract

本研究紅外線硬銲接合Ti-15-3鈦合金與Ti50Ni50鈦鎳形狀記憶合金、同質接合CoCrFeMnNi高熵合金(HEA)、異質接合CoCrFeMnNi/CoCrFeNi (HEAs)與316不鏽鋼(SS)，以及同質接合HfNbTiZr HEA，探討不同實驗參數下填料對於基材之潤濕性、顯微組織演化、剪應力強度以及破壞模式等。研究結果發現，BAg-8填料於Ti-15-3基材之潤濕性，可藉由添加4.5wt.%之鈦改善，使用BAg-8者破壞於Cu(Ti,V)及富銀相之間，用Ticusil®填料者則位於銲道中的Ti2Ni介金屬相。BNi-2及MBF601填料於CoCrFeMnNi基材之潤濕性於液相線溫度50 °C之上時相當優秀；CoCrFeMnNi/BNi-2/CoCrFeMnNi銲道主要由富鎳相基地、大顆CrB以及細小的硼化物所組成，其剪力強度會隨硬銲時間及溫度的增加而增加；接合CoCrFeMnNi /MBF601/ CoCrFeMnNi之最佳條件為1050 °C持溫600秒，其剪力強度為321 MPa，當於1080 °C接合時，因產生恆溫凝固縮孔使其剪力強度下降。異質接合CoCrFeMnNi/316 SS和同質皆合CoCrFeMnNi之結果相似；接合CoCrFeNi/BNi-2/316 SS時，最佳條件為1020°C持溫600秒，破壞於銲道中之CrB化合物；CoCrFeNi/MBF601/316 SS銲道由富鐵鎳相、磷化物及B/Cr/Fe/P化合物所組成，其最佳剪力強度324MPa。AuPdNi填料於CoCrFeMnNi/CoCrFeNi基材之潤濕性於1050°C時非常優秀；使用紅外線爐及傳統爐硬銲CoCrFeNi/AuPdNi/CoCrFeNi時，其銲道由富金相及富鎳相所組成，剪力強度皆大於300 MPa，且為延性破壞；CoCrFeMnNi/AuPdNi/CoCrFeMnNi銲道由CoCrFeNi相、富鎳相以及AuMn相所組成，但使用傳統爐因產生恆溫凝固縮孔導致其剪力強度較低。Ti-15Cu-15Ni填料於HfNbTiZr基材於970°C及1000 °C之潤濕性都非常良好，但Ti-20Cu-20Ni-20Zr填料於870°C及900 °C之潤濕性皆不佳。

In this study, different braze fillers are used to infrared brazing of Ti-15-3 alloy with Ti50Ni50 shape memory alloy, CoCrFeMnNi with CoCrFeMnNi high entropy alloy (HEA), CoCrFeMnNi/CoCrFeNi HEAs with 316 stainless steel (SS) and HfNbTiZr with HfNbTiZr HEA. Experimental results indicate that BAg-8 and Ticusil® fillers can wet Ti-15-3 substrate and the wettability greatly increases by alloyed with 4.5 wt.% Ti. For BAg-8 brazed joint, cracks propagate at the location between the interfacial Cu(Ti,V) and the Ag-rich phase. In Ticusil® brazed joint, cracks propagate along the central Ti2Ni intermetallics. The wettability of BNi-2 and MBF601 fillers on CoCrFeMnNi substrate is great at 50 °C above their liquidus temperatures. The CoCrFeMnNi/BNi-2/CoCrFeMnNi joints are dominated by Ni-rich matrix with huge CrB and a few tiny boride precipitates, and shear strengths of joints increase with increasing brazing temperature/time. The CoCrFeMnNi/MBF601/CoCrFeMnNi joint brazed at 1050 °C has the highest shear strength of 321 MPa, while that brazed at 1080 °C has a lower shear strength because of solidification shrinkage voids. The CoCrFeMnNi/316 SS joints have similar results like CoCrFeMnNi/CoCrFeMnNi joints. The CoCrFeNi/BNi-2/316 SS joint has the highest shear strength of 374 MPa and fractures at the CrB in the joint. The CoCrFeNi/MBF601/316 SS joint consists of a (Fe,Ni)-rich matrix, phosphides and B/Cr/Fe/P compounds, and has the highest shear strength of 324 MPa. The wettability of AuPdNi filler on CoCrFeNi/CoCrFeMnNi substrates is excellent at 1050°C. CoCrFeNi/AuPdNi/CoCrFeNi joints brazed using infrared and traditional furnaces are composed of Au/Ni-rich phases, and the shear strengths exceed 300 MPa with dimple fracture surfaces. CoCrFeMnNi/AuPdNi/CoCrFeMnNi brazed joints are composed of CoCrFeNi/Ni-rich phases and AuMn intermetallics, but the traditional furnace brazed joint has a much lower shear strength because of solidification shrinkage voids. The wettability of Ti-15Cu-15Ni on HfNbTiZr RHEA is great at 970 °C and 1000 °C, but that of Ti-20Cu-20Ni-20Zr is poor at 870 °C and 900 °C.