TA2/TA15 graded structural material（GSM） was fabricated by the laser additive manufacturing（LAM） process. The chemical composition, microstructure and micro-hardness of the as-deposited GSM were investigated. The ...TA2/TA15 graded structural material（GSM） was fabricated by the laser additive manufacturing（LAM） process. The chemical composition, microstructure and micro-hardness of the as-deposited GSM were investigated. The results show that the TA2 part of exhibiting near-equiaxed grains was Widmanst？tten α-laths microstructure. The TA15 part containing large columnar grains was fine basket-weave microstructure. The graded zone was divided into four deposited layers with 3000 μm in thickness. As the distance from the TA2 part increases, the alloy element contents and the β phase volume fraction increase, the α phase volume fraction decreases and the microstructure shows the evolution from Widmanst？tten α-laths to basket-weave α-laths gradually. The micro-hardness increases from the TA2 part to the TA15 part due to the solid solution strengthening and grain boundary strengthening.展开更多
以Cr2O3、Ta2O5和纳米碳黑为原料,在开放体系的流动N2气氛条件下,采用碳热还原氮化法制备出了(Cr,Ta)2CN固溶体粉末,利用XRD、SEM、EDS等分析测试手段对制备过程中的物相演变规律和微观形貌变化进行了研究。研究结果表明,碳热还原氮化...以Cr2O3、Ta2O5和纳米碳黑为原料,在开放体系的流动N2气氛条件下,采用碳热还原氮化法制备出了(Cr,Ta)2CN固溶体粉末,利用XRD、SEM、EDS等分析测试手段对制备过程中的物相演变规律和微观形貌变化进行了研究。研究结果表明,碳热还原氮化法制备(Cr,Ta)2CN固溶体粉末过程中物相演变顺序为Cr2O3、Ta2O5、C→Cr2O3、Cr3C2、Cr7C3、Cr Ta O4、C→Cr2O3、Cr7C3、Cr Ta O4→(Cr,Ta)2CN。在N2流量为500 m L/min、烧结温度为1 500℃保温2 h的条件下,可制备出粒度约5μm、游离碳和氧含量分别为0.16%,0.085%的单相(Cr,Ta)2CN固溶体粉末。展开更多
The dependences of the microstructure and hardness of the binary Cr Ta alloys [Cr 9.0, 9.2, 9.4, 9.6, 9.8, and 13.0 Ta] (mole fraction, %) were investigated. When Ta content of the alloy is less than 9.4%, there are p...The dependences of the microstructure and hardness of the binary Cr Ta alloys [Cr 9.0, 9.2, 9.4, 9.6, 9.8, and 13.0 Ta] (mole fraction, %) were investigated. When Ta content of the alloy is less than 9.4%, there are primary dendrite grains of a Cr solid solution phase existing in the matrix of Cr Cr 2Ta eutectic colonies in the alloy. Moreover, the regular polygon grains of the primary Cr 2Ta Laves phase are surrounded by the Cr Cr 2Ta eutectic colony in the hyper eutectic Cr 9.4% Ta alloys. The scanning electron microphotograph shows that one of the Cr 2Ta phase plates of an eutectic colony always connects with the primary Cr 2Ta Laves phase grain in a hyper eutectic alloy. The eutectic colony size of Cr Ta alloys decreases with increasing Ta. In addition, the macrohardness of Cr Ta alloys is influenced by the chemical composition at room temperature. The binary eutectic Cr Ta alloy presents the lowest hardness on a macrohardness scale.展开更多
基金Project(2010CB731705)supported by the National Basic Research Program of China
文摘TA2/TA15 graded structural material（GSM） was fabricated by the laser additive manufacturing（LAM） process. The chemical composition, microstructure and micro-hardness of the as-deposited GSM were investigated. The results show that the TA2 part of exhibiting near-equiaxed grains was Widmanst？tten α-laths microstructure. The TA15 part containing large columnar grains was fine basket-weave microstructure. The graded zone was divided into four deposited layers with 3000 μm in thickness. As the distance from the TA2 part increases, the alloy element contents and the β phase volume fraction increase, the α phase volume fraction decreases and the microstructure shows the evolution from Widmanst？tten α-laths to basket-weave α-laths gradually. The micro-hardness increases from the TA2 part to the TA15 part due to the solid solution strengthening and grain boundary strengthening.
文摘以Cr2O3、Ta2O5和纳米碳黑为原料,在开放体系的流动N2气氛条件下,采用碳热还原氮化法制备出了(Cr,Ta)2CN固溶体粉末,利用XRD、SEM、EDS等分析测试手段对制备过程中的物相演变规律和微观形貌变化进行了研究。研究结果表明,碳热还原氮化法制备(Cr,Ta)2CN固溶体粉末过程中物相演变顺序为Cr2O3、Ta2O5、C→Cr2O3、Cr3C2、Cr7C3、Cr Ta O4、C→Cr2O3、Cr7C3、Cr Ta O4→(Cr,Ta)2CN。在N2流量为500 m L/min、烧结温度为1 500℃保温2 h的条件下,可制备出粒度约5μm、游离碳和氧含量分别为0.16%,0.085%的单相(Cr,Ta)2CN固溶体粉末。
文摘The dependences of the microstructure and hardness of the binary Cr Ta alloys [Cr 9.0, 9.2, 9.4, 9.6, 9.8, and 13.0 Ta] (mole fraction, %) were investigated. When Ta content of the alloy is less than 9.4%, there are primary dendrite grains of a Cr solid solution phase existing in the matrix of Cr Cr 2Ta eutectic colonies in the alloy. Moreover, the regular polygon grains of the primary Cr 2Ta Laves phase are surrounded by the Cr Cr 2Ta eutectic colony in the hyper eutectic Cr 9.4% Ta alloys. The scanning electron microphotograph shows that one of the Cr 2Ta phase plates of an eutectic colony always connects with the primary Cr 2Ta Laves phase grain in a hyper eutectic alloy. The eutectic colony size of Cr Ta alloys decreases with increasing Ta. In addition, the macrohardness of Cr Ta alloys is influenced by the chemical composition at room temperature. The binary eutectic Cr Ta alloy presents the lowest hardness on a macrohardness scale.
