采用选区激光熔融(selective laser melting, SLM)法制备Cu-Cr-Nb-Ce合金,通过对合金进行1 000 ℃高温热处理,研究Cu-Cr-Nb-Ce合金显微组织、力学性能和导电性能的高温稳定性。结果表明,在SLM成形件的XY面(垂直于建造方向),基体组织由熔池道中心的长柱状晶和沿熔池道边界分布的细小等轴晶组成,两者交错分布,平均晶粒尺寸为28.3 μm,第二相为在基体中弥散分布的纳米级Cr2Nb相。SLM成形件经1 000 ℃高温热处理10、50和100 h后,晶粒的整体形貌无明显变化,但平均晶粒尺寸分别增加8.5%、18.7%和27.2%;Cr2Nb相的平均尺寸从29.5 nm分别长大到348.6、524.9和589.4 nm,最大尺寸达1~3 μm,并且在晶界分布更密集;合金的维氏硬度(HV)明显下降,从126分别降至84、79和75。经10 h热处理,电导率从18.5%IACS显著提高到54.6%IACS,延长热处理时间,则电导率不再明显提高。
Cu-Cr-Nb-Ce alloy was fabricated by selective laser melting (SLM). The high-temperature stability of microstructure, mechanical properity and electrical conductivity of Cu-Cr-Nb-Ce alloy was studied by high-temperature heat treatment at 1 000 ℃. The results show that the matrix mocrostructure of the XY plane (perpendicular to the build direction) of the as-SLMed Cu-Cr-Nb-Ce alloy is composed of long columnar grains in the center of the molten pool and fine equiaxed grains distributed along the boundary of the molten pool. The two kinds of grains are staggered and the average grain size is 28.3 μm. The second phase are the nanoscale Cr2Nb phases dispersed in the matrix. After heat treatment at 1 000 ℃ for 10, 50 and 100 h, the overall morphology of the grains does not change obviously, but the grains grow and the average size of grain increases by 8.5%, 18.7% and 27.2%, respectively; The average size Cr2Nb phase grows from 29.5 nm to 348.6 nm, 524.9 nm and 589.4 nm respectively, and the maximum size reaches 1-3 μm. In addition, Cr2Nb phases in heat-treated specimens are more densely along the grain boundary. The hardness (HV) of the alloy decreases significantly from 126 to 84, 79 and 75 respectively; while the electrical conductivity increases significantly from 18.5%IACS to 54.6%IACS after heat treatment for 10 h, whereas no significant progress is observed with extension of the heat treatment time.
[1] LU L, SHEN Y F, CHEN X H, et al.Ultrahigh strength and high electrical conductivity in copper[J]. Science, 2004, 304(5669): 422-426.
[2] CHBIHI A, SAUVAGE X, BLAVETTE D.Atomic scale investigation of Cr precipitation in copper[J]. Acta Materialia, 2012, 60(11): 4575-4585.
[3] 赵凡, 刘祖铭, 吕学谦, 等. 粉末冶金Cu-Cr-Zr合金的形变热处理组织及性能[J]. 粉末冶金材料科学与工程, 2019, 24(4): 385-390.
ZHAO Fan, LIU Zuming, LÜ Xueqian, et al.Microstructure and properties of powder metallurgical Cu-Cr-Zr alloy by heat-treatment and deformation[J]. Materials Science and Engineering of Powder Metallurgy, 2019, 24(4): 385-390.
[4] ZENG H, SUI H, WU S J, et al.Evolution of the microstructure and properties of a Cu-Cr-(Mg) alloy upon thermomechanical treatment[J]. Journal of Alloys and Compounds, 2021, 857: 157582.
[5] FU S L, LIU P, CHEN X H, et al.Effect of aging process on the microstructure and properties of Cu-Cr-Ti alloy[J]. Materials Science and Engineering A, 2021, 802: 140598.
[6] XU S, FU H D, WANG Y T, et al.Effect of Ag addition on the microstructure and mechanical properties of Cu-Cr alloy[J]. Materials Science and Engineering A, 2018, 726: 208-214.
[7] MA M Z, LI Z, XIAO Z, et al.Microstructure and properties of a novel Cu-Cr-Yb alloy with high strength, high electrical conductivity and good softening resistance[J]. Materials Science and Engineering A, 2020, 795: 140001.
[8] KAZANTZIS A V, AINDOW M, JONES I P, et al.The mechanical properties and the deformation microstructures of the C15 Laves phase Cr2Nb at high temperatures[J]. Acta Materialia, 2007, 55(6): 1873-1884.
[9] DE GROH H C, ELLIS D L, LOEWENTHAL W S. Comparison of GRCop-84 to other Cu alloys with high thermal conductivities[J]. Journal of Materials Engineering and Performance, 2008, 17(4): 594-606.
[10] MINNECI R P, LASS E A, BUNN J R, et al.Copper-based alloys for structural high-heat-flux applications: a review of development, properties, and performance of Cu-rich Cu-Cr-Nb alloys[J]. International Materials Reviews, 2020, 66(11): 1-32.
[11] DHOKEY N B, SARVE S N, LAMSOGE H A.Development of in-situ synthesis of Cr2Nb reinforced copper alloy by aluminothermic process[J]. Transactions of the Indian Institute of Metals, 2011, 64(4/5): 425-429.
[12] SHUKLA A K, NARAYANA MURTY S V S, KUMAR R S, et al. Densification behavior and mechanical properties of Cu-Cr-Nb alloy powders[J]. Materials Science and Engineering A, 2012, 551: 241-248.
[13] SHUKLA A K, NARAYANA MURTY S V S, KUMAR R S, et al. Effect of powder milling on mechanical properties of hot-pressed and hot-rolled Cu-Cr-Nb alloy[J]. Journal of Alloys and Compounds, 2013, 580: 427-434.
[14] SHUKLA A K, NARAYANA MURTY S V S, KUMAR R S, et al. Spark plasma sintering of dispersion hardened Cu-Cr-Nb alloy powders[J]. Journal of Alloys and Compounds, 2013, 577: 70-78.
[15] SELTZMAN A H, WUKITCH S J.Precipitate size in GRCop-84 gas atomized powder and laser powder bed fusion additively manufactured material[J]. Fusion Science and Technology, 2021, 77(7/8): 1-6.
[16] SELTZMAN A H, WUKITCH S J.Fracture characteristics and heat treatment of laser powder bed fusion additively manufactured GRCop-84 copper[J]. Materials Science and Engineering A, 2021, 827: 141690.
[17] SELTZMAN A H, WUKITCH S J.Resolution and geometric limitations in laser powder bed fusion additively manufactured GRCop-84 structures for a lower hybrid current drive launcher[J]. Fusion Engineering and Design, 2021, 173: 112847.
[18] GROZA J R.Microstructural features of a new precipitation- strengthened Cu-8Cr-4Nb alloy[J]. Materials Characterization, 1993, 31(3): 133-141.
[19] SHUKLA A K, NARAYANA MURTY S V S, SHARMA S C, et al. Aging behavior and microstructural stability of a Cu- 8Cr-4Nb alloy[J]. Journal of Alloys and Compounds, 2014, 590: 514-525.
[20] ANDERSON K R, GROZA J R, DRESHFIELD R L, et al.High-performance dispersion-strengthened Cu-8Cr-4Nb alloy[J]. Metallurgical and Materials Transactions A, 1995, 26(9): 2197-2206.
[21] 任亚科. 选区激光熔化制备Cu-Cr-Nb合金的显微组织与性能研究[D]. 长沙: 中南大学, 2021.
REN Yake.Microstructure and properties of Cu-Cr-Nb alloy fabricated by selective laser melting[D]. Changsha: Central South University, 2021.
[22] 吕学谦. 粉末冶金Cu-Cr-Nb-Ce合金的显微组织调控及性能研究[D]. 长沙: 中南大学, 2020.
LÜ Xueqian.Study on microstructure adjust and properties of powder metallurgically prepared Cu-Cr-Nb-Ce alloy[D]. Changsha: Central South University, 2020.
[23] ZINKLE S, FABRITSIEV S.Copper alloys for high heat flux structure applications[J]. Atomic and Plasma-Material Interaction Data for Fusion, 1994, 5: 163-191.
[24] 国家标准化管理委员会. 铜合金硬度与强度换算值: GB/T 3771-1983[S]. 北京: 中国标准出版社, 1983.
Standardization Administration.Conversion of hardness and strength of copper alloys: GB/T 3771-1983[S]. Beijing: China Standard Press, 1983.
