摘要:
采用变温超固相线液相烧结(SupersolidusLiquid Phase Sintering，SLPS)工艺，进行真空无压烧结制备高密度A100高合金钢材料，并分析其烧结致密化机理。通过金相显微镜、扫描电镜、拉伸实验和密度、硬度测试研究了粉末粒径、压制及烧结工艺参数对粉末冶金A100钢致密度、微观组织及力学性能的影响。结果表明：烧结致密化速率随粒径减小而增大，变温SLPS烧结可有效促进合金致密化。采用粒径为7.3～20.8 μm粉末，加入0.7 wt.%丁苯橡胶成形剂混合均匀，进行40目擦筛造粒，单向压制成型后，1440 ℃保温10 min后降温至1430 ℃保温72 min烧结，致密度高达99.4 %，抗拉强度达1700 MPa以上。烧结过程中变温烧结试样在高温段通过粘性流动和颗粒重排迅速致密，低温段以溶解-再析出机制使颗粒形状相适应，有效提升合金致密度。
Abstract:
A variable-temperature supersolidus liquid phase sintering (SLPS) process was employed to fabricate high-density A100 high-alloy steel through vacuum pressureless sintering, with systematic investigation of the sintering densification mechanisms. The effects of powder particle size, compaction parameters, and sintering conditions on the densification, microstructure, and mechanical properties of powder metallurgy A100 steel were analyzed using optical microscopy, scanning electron microscopy (SEM), tensile testing, and density/hardness measurements. The results indicated that the sintering densification rate increased with decreasing particle size, and the variable-temperature SLPS process significantly enhanced alloy densification. By utilizing powders with a particle size range of 7.3–20.8 μm, mixed with 0.7 wt.% styrene-butadiene rubber (SBR) binder, granulated through 40-mesh sieving, and uniaxially pressed, the specimens achieved a density of 99.4 % and tensile strength exceeding 1700 MPa after sintering at 1440 ℃ for 10 min followed by 1430 ℃ for 72 min. During sintering, the variable-temperature profile promoted rapid densification via viscous flow and particle rearrangement at the high-temperature stage, while the dissolution-reprecipitation mechanism at the low-temperature stage optimized particle morphology adaptation, collectively improving densification efficiency.
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