Selective Laser Melting Additive Manufactured Tantalum: Effect of Microstructure and Impurities on the Strengthening-Toughing Mechanism

Fengjun Lian; Longqing Chen; Changgui Wu; Zhuang Zhao; Jingang Tang; Jun Zhu

doi:10.3390/ma16083161

Selective Laser Melting Additive Manufactured Tantalum: Effect of Microstructure and Impurities on the Strengthening-Toughing Mechanism

Materials (Basel). 2023 Apr 17;16(8):3161. doi: 10.3390/ma16083161.

Authors

Fengjun Lian¹, Longqing Chen², Changgui Wu¹, Zhuang Zhao³, Jingang Tang³, Jun Zhu¹

Affiliations

¹ College of Physics, Sichuan University, Chengdu 610065, China.
² Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China.
³ Institute of Machinery Manufacturing Technology, China Academy of Engineering Physics, Mianyang 621900, China.

Abstract

The balance between the strength and the toughness of pure tantalum (Ta) fabricated with selective laser melting (SLM) additive manufacturing is a major challenge due to the defect generation and affinity for oxygen and nitrogen. This study investigated the effects of energy density and post-vacuum annealing on the relative density and microstructure of SLMed tantalum. The influences of microstructure and impurities on strength and toughness were mainly analyzed. The results indicated that the toughness of SLMed tantalum significantly increased due to a reduction in pore defects and oxygen-nitrogen impurities, with energy density decreasing from 342 J/mm³ to 190 J/mm³. The oxygen impurities mainly stemmed from the gas inclusions of tantalum powders, while nitrogen impurities were mainly from the chemical reaction between the molten liquid tantalum and nitrogen in the atmosphere. The proportion of <110> texture decreased after vacuum-annealing at 1200 °C, while that of the <100> texture increased. Concurrently, the density of dislocations and small-angle grain boundaries significantly decreased while the resistance of the deformation dislocation slip was significantly reduced, enhancing the fractured elongation up to 28% at the expense of 14% tensile strength.

Keywords: impurity; selective laser melting; strength; tantalum; toughness.

Grants and funding

This work has been supported by the Department of Science and Technology of Sichuan Province under grant numbers (2021YFH0174, 2022YFG0102) and the Strategic Cooperation Projects fostered by Zigong Government and Sichuan University (No. 2021CDZG-22).