激光直接沉积TC11/TC17双合金的组织及性能

Microstructure and Tensile Properties of TC11/TC17 Dual Alloy Fabricated with Direct Laser Melting Method

摘要:

研究了直接连接及梯度连接两种激光直接沉积TC17/TC11双合金的显微组织及力学性能。结果表明，两种连接方式成形的TC17/TC11双合金均可分为TC17均一成分区、过渡区及TC11均一成分区三个区域，沉积态下，两种连接方式均一成分区显微组织呈层带状周期分布；直接连接TC17/TC11双合金过渡区极窄，两侧化学成分、显微组织在交界处发生突变；梯度连接TC17/TC11双合金过渡区厚度较大，过渡区化学成分呈连续过渡，显微组织受成分变化和热循环双重影响，呈介于TC17和TC11中间态显微组织；直接连接过渡区显微硬度存在突变，梯度连接过渡区显微硬度由TC17侧逐渐过渡至TC11侧；直接连接和梯度连接样品室温拉伸断裂位置均在TC11均一成分区，强度接近，延伸率分散度较大。

Abstract:

The microstructure and tensile properties of TC17/TC11 dual alloy fabricated with direct laser melting deposition method using two connecting processes (direct connection and gradient connection) were investigated. The results show that, according to composition changes, the TC17/TC11 dual alloy can be divided into three parts: uniform TC17 zone, transition zone and uniform TC11 zone. The as-deposited microstructure of uniform TC17 and TC11 zones shows cyclic layer-like characteristics. For direct connection process, there exists a extremely narrow transition zone between TC17 and TC11 zones. Sharp changes of both chemical composition, microstrucuture and microhardness are found between uniform TC17 and TC11 zones. For gradient connection process, the transition zone encompasses a wider region in which continuous changes of chemical composition and microhardness is found. The intermediate microstructure which is different from TC17 and TC11 emerges in the gradient transition zone. Room temperature tensile tests show that all as-deposited dual alloy samples regardless of connecting process are fractured in the TC11 zone, with approximate tensile strengths and dispersed elongations.