Microstructure and properties of pure molybdenum block prepared by selective electron beam melting
LI Huixia1, ZHU Jilei1, TAN Yannni2, LIU Bin2, CHEN Rui1, ZHAO Pei1, YI Yang1
1. Xi'an Sailong Metal Materials Co., Ltd., Xi'an 710018, China; 2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
Abstract The block of pure molybdenum was fabricated for the first time by selective electron beam melting. Its impurities, microstructure, density and micro-hardness were tested using chemical analysis, metallurgical microscopy, chemical balance and microhardness tester. The results show that the impurity increments of the as-build pure molybdenum such as C, N, O and H are not more than 0.001%. Using a single-melting process, the microstructure of pure molybdenum along the deposition direction present scoarse columnar crystal characteristics, and there are a few microcracks along the columnar grain boundary. Using a double-melting process, the grain size is refined and the microcrack phenomenon is suppressed. The better selective electron beam double-melting process is as follows: the primary melting current is 12 mA, and the velocity is 0.6 m/s; the secondary melting current is 12 mA, and the velocity is 0.89 m/s. Under the better process, the relative density of the as-build pure molybdenumblock is higher than 99% with a density of (10.15±0.13) g/cm3. The microhardness (HV0.2) is 185-200 and shows no anisotropy.
LI Huixia,ZHU Jilei,TAN Yannni, et al. Microstructure and properties of pure molybdenum block prepared by selective electron beam melting[J]. Materials Science and Engineering of Powder Metallurgy, 2020, 25(6): 497-504.
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