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激光立体成形Ti-80%Ni合金显微组织及力学性能许小静1,2,林鑫1,黄卫东2,王亮0(1.陕西省西安市西北工业大学凝固技术国家重点实验室2.北京市航天材料及工艺研究所)摘 要:采用激光立体成形技术制备了Ti-80%Ni(质量分数)合金,研究了工艺参量对显微组织和力学性能的影响.结果表明,激光立体成形Ti-80%Ni合金由η-TiNi3板条和TiNi(B2)+η共晶构成.随着激光扫描速率的增大,η板条逐渐转变为η板条+(TiNi(B2)+η)共晶,η板条尺寸随着扫描速率的增大而减小;随着激光功率的增大,共晶体积分数逐渐增大,η板条逐渐碎断转变为一定取向的块状组织,功率越大,块状组织越细,形成(TiNi(B2)+η)离异共晶组织+板块间(TiNi(B2)+η)共晶组织.激光扫描速率和激光功率的增大均导致硬......
分析.结果表明:合金经β锻造后的组织由少量α2颗粒,大量O相板条和B2相基体组成.在固溶处理过程中,组织中的O相板条发生溶解,数量减少,形状变短,变粗.在980 ℃以上固溶处理时,基体B2相发生明显的再结晶.固溶+时效处理后,细小的二次O相板条再次从B2基体中析出,并最终形成一种具有短棒状或颗粒状的初生α2/O相+细小的二次O相板条+B2相基体组成的组织.随着微观组织中初生α2/O相数量的减少,二... that after β-forging the microstructure is composed of a large number of O phase laths, a few a2 particles and B2 matrix. During solution treatment, the O phase lamellae in the microstructure solves......
and the B2 matrix is determined. In the NiTi samples aged at 573 and 723 K, fine and homogeneous Ni4Ti3 precipitates are coherent with the B2 austenite matrix. The Ni4Ti3 particles precipitate in the grain interior and at the grain boundaries, where the heterogeneous Ni4Ti3 precipitates are coherent, semi-coherent and incoherent with the B2 matrix in the NiTi sample aged at 873 K. As for the NiTi......
合金显微结构和力学性能的影响.结果表明:复合含Nb-Zr的TiAl合金的α2+γ层片组织显示出较高的热力学稳定性,合金的α2+γ层片晶团在热暴露过程中,α2→γ和α2+γ→B2(ω)相变并不普遍.合金中B2(ω)晶粒由若干微米胞构成,长期的高温热暴露导致胞壁处具有较高有序度的D88相结构的ω颗粒明显长大,且胞内也大量析出这种脆性的D88相结构的ω颗粒;同时,在B2(ω)晶内还析出微米级别的γ相,这... and the formation of B2(ω) through α2+γ→B2(ω) are not prevail inside the α2+γ colonies. This tends to suggest that the α2+γ lamellae are at a high level of thermodynamic stability. B2(ω) grains consist......
at.%) equimolar FeCoCrNiMn high-entropy alloy (HEA) after being annealed at 500 °C were investigated. This single face-centered cubic (FCC) solid-solution HEA decomposed to M23C6+L10, B2, and σ in chronological order. The formation kinetics of the L10, B2, and σ phases followed the Johnson-Mehl-Avrami- Kolmogorov (JMAK) equation. The yield strength of the HEA was 1520 MPa and increased to 1920 MPa......
应. 结果表明: 温度记忆效应仅在Ti-Ni-Cu合金的逆转变加热过程出现, 在单斜结构马氏体与母相逆相变(B19′→B2)及正交结构马氏体与母相逆相变(B19→B2)过程中均能发生温度记忆效应; 在随后的完全循环过程中, 温度记忆记忆效应不再出现, DSC相变曲线又"恢复"到其原始形态; 而在马氏体相变冷却过程中未发现温度记忆效应. 分析表明, 不完全相变过程中的弹性能再分布是可能的温度记忆效应... scanning calorimeter. The results indicate that TME of Ti-Ni-Cu alloy only exists in the heating process, and TME occurs both in B19′→B2 and B19→B2 transformation during heating process......
calorimetry (DSC) analysis. The results show that the matrix of the Ni50Ti50 alloy consists of both B19′ (martensite) phase and B2 (austenite) phase. Moreover, the substructures of twins could be observed in the B19′ phase. However, the ternary alloys of NiTiFe exhibit B2 phase in the microstructures. Such microstructures were also characterized by large presence of Ti2Ni precipitates dispersed homogenously......
)5元系合金,采用扫描电镜,透射电镜与多种力学性能实验设备,开展合金相区温度区间,β/B2锻造与热处理过程的组织演化及力学性能响应关系研究.结果表明:合金由高温至低温依次经历B2,B2+α2,B2+α2+O,B2+O四个相区,分别对应1060℃,950℃和930℃三个临界温度.β/B2锻造合金组织中B2晶界相的组成与形态受B2相的畸变强度与热处理共同作用,粗大断续的α2相易于在强畸变的原始B2相晶界形成,并在B2+O相区热处理过程中转变为α2+Orim结构;细小连续的O相易形成于弱畸变的动态再结晶B2相晶界,经B2+α2相区热处理可完全转变为α2相;静态再结晶晶界基本无晶界相.B2相晶内析出相主要受热处理影响,α2相和O相均可由B2相直接独立析出,O相也可依附α2相生成,形成α2/Orim核壳结构,表明α2相核具备良好的低温稳定性;固溶+时效处理后,基体B2相晶内均呈现由大,小两套析出相组......
are composed of the single FCC phase. The BCC and B2 phases are found. It is confirmed that the BCC phase in the Al7Cr20Fe66Ni7 alloy is transformed from the FCC phase at about 900 °C during cooling. While in the 800 °C-annealed Al7Cr20Fe60Ni13 alloy, the FCC phase is stable and the hardness decreases. After annealing at 1000 °C, for the precipitation of the B2 particles, the Al......
的高温热稳定性,采用透射电镜和扫描电镜观察合金的显微组织变化并测试相应的力学性能.研究发现:长期大气高温热暴露导致合金中α2+γ层片晶团内的α2层片发生了一定程度的α2?γ相变:部分α2层片转变成为细小的γ层片,到10 000 h时,α2层片的原始厚度减少了约一半.长期大气高温热暴露也导致合金中α2+γ层片条束上发生了α2+γ→B2(ω)相变:条束上部分α2+γ消失,代之以微米及亚微米尺度的B2(ω)块状相.在10 000 h时,其面积分数达到8.4%,随着高温热暴露的逐渐进行,合金的室温塑性伸长率逐渐降低.在10 000 h时,合金的塑性约为热暴露前的2/3,表明在复合含Nb+Hf的TiAl合金中,热暴露所导致的"释氧脆化"和"B2+ω生成脆化"的影响有限.复合含Nb+Hf的TiAl合金具有优于单纯含Nb的TiAl合金的高温热稳定性. 长期高温热暴露对合金的断裂强度和条件屈服强度没有明显......