Effect of Aging Treatments on Microstructure and Exfoliation Corrosion Behavior of Spray Forming 7075 Alloy

2013 ◽  
Vol 774-776 ◽  
pp. 872-875 ◽  
Author(s):  
Rui Ming Su ◽  
Ying Dong Qu ◽  
Rong De Li ◽  
Qi Ming Xie ◽  
Yu Sheng Wu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Tensile Strength ◽  
Grain Boundaries ◽  
Volume Fraction ◽  
Spray Forming ◽  
Exfoliation Corrosion ◽  
Transmission Electron ◽  
Peak Aging ◽  
7075 Alloy

Mechanical properties, microstructure and exfoliation corrosion (EXCO) behavior of spraying forming 7075 alloy underwent retrogression and re-aging (RRA) were studied by tensile test, transmission electron microscopy and EXCO test, and compared with those of T6 peak aging and T73 overaging treatments. The results show that after T6 treatment, abundance transgranular dispersive η phases make tensile strength of the alloy reach 760MPa, elongation and EXCO rating are only 4.8% and ED respectively by dint of continuous η phases at grain boundaries and narrow precipitate free zones (PFZ). After T73 treatment, interrupted η phases at grain boundaries and wide PFZ can improve elongation and EXCO resistance, but depressed volume fraction of coarsening transgranular η phases reduce tensile strength to 676MPa. After RRA treatment (120°C/24h + 200°C/10min + 120°C/24h), abundance transgranular dispersive η phases separate out again, η phases at grain boundaries interrupt, and PFZ widen slightly. Tensile strength, elongation and EXCO rating of alloy are 758MPa, 8.4% and EA respectively.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

Mechanical Properties and Microstructure Evolution of Typical Over-Aging State Al-Zn-Mg-Cu Alloy during Thermal Exposure

2021 ◽  
Vol 1026 ◽  
pp. 84-92
Author(s):  
Tao Qian Cheng ◽  
Zhi Hui Li
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Mechanical Property ◽  
Electrical Conductivity ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Thermal Exposure ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Thermal Stability Of

Al-Zn-Mg-Cu alloy have been widely used in aerospace industry. However, there is still a lack of research on thermal stability of Al-Zn-Mg-Cu alloy products. In the present work, an Al-Zn-Mg-Cu alloy with T79 and T74 states was placed in the corresponding environment for thermal exposure experiments. Performance was measured by tensile strength, hardness and electrical conductivity. In this paper, precipitation observation was analyzed by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HREM). The precipitations of T79 state alloy were GPⅡ zone, η' phase and η phase while the ultimate tensile strength, hardness and electrical conductivity were 571MPa, 188.2HV and 22.2MS×m-1, respectively. The mechanical property of T79 state alloy decreased to 530MPa and 168.5HV after thermal exposure. The diameter of precipitate increased and the precipitations become η' and η phase at the same time. During the entire thermal exposure, T74 state alloy had the same mechanical property trend as T79 state alloy. The precipitate diameter also increased while the types of precipitate did not change under thermal exposure. The size of precipitates affected the choice of dislocation passing through the particles to affect the mechanical properties.

scholarly journals Effect of Cu on the Fracture and Exfoliation Corrosion Behavior of Al-Zn-Mg-xCu Alloy

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1048 ◽  
Author(s):  
Huibin Jiao ◽  
Kanghua Chen ◽  
Songyi Chen ◽  
Zhen Yang ◽  
Peng Xie ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Exfoliation Corrosion ◽  
Cu Content ◽  
Short Transverse ◽  
Transmission Electron ◽  
Corrosion Behaviors ◽  
Mechanical Tensile ◽  
Scanning Electron ◽  
Better Than

In the present work, the influence of Cu content on microstructure, mechanical properties and exfoliation corrosion behaviors of Al-Zn-Mg-xCu alloy extrusions has been investigated in longitudinal-transverse (L-T) and short-longitudinal (S-L) directions by means of mechanical tensile and exfoliation corrosion testing combined with optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that a higher Cu content significantly decreased the fracture toughness and ductility of the alloy in S-L direction compared with L-T direction. Concomitant with the increase in Cu content, a transition in fracture mode was observed from transgranular dimpled rupture to intergranular rupture in S-L direction. Moreover, the exfoliation corrosion (EXCO) resistance of the alloy decreased as the Cu content increased and the exfoliation corrosion resistance of the alloy in short-transverse (S-T) direction was better than that of L-T direction. These results were mainly associated with the large number of coarse intermetallics caused by high Cu content in the L-T direction of alloy.

scholarly journals Research on the Microstructures and Mechanical Properties of Bainite/Martensite Rail Treated by the Controlled-Cooling Process

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3061 ◽  
Author(s):  
Jiajia Qiu ◽  
Min Zhang ◽  
Zhunli Tan ◽  
Guhui Gao ◽  
Bingzhe Bai
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Toughness ◽  
Electron Backscatter Diffraction ◽  
Microstructural Characterization ◽  
Cooling Process ◽  
Controlled Cooling ◽  
Transmission Electron ◽  
Backscatter Diffraction

A bainite/martensite multiphase rail is treated by the controlled-cooling process with different finish-cooling temperatures. The simulated temperature–time curves of the position of 5 mm and 15 mm below the rail tread (P5 and P15) express different trends. P5 has greater impact toughness and lower tensile strength than P15. Microstructural characterization was carried out by conducting scanning electron microscopy, X-ray diffraction, electron backscatter diffraction, and transmission electron microscopy. The greater tensile strength is due to the dispersed ε-carbides hindering the movement of dislocations. The greater impact toughness is attributed to the filmy retained austenite and the smaller effective grain with high-angle boundary. Finite element modeling (FEM) and microstructural characterization reasonably explain the changes of mechanical properties. The present work provides experimental and theoretical guidance for the development of rail with excellent mechanical properties.

Phase Stability and Mechanical Properties of C-22 Alloy Aged in the Temperature Range 590 to 760°C for 16,000 Hours

1999 ◽  
Vol 556 ◽  
Author(s):  
Tammy S. Edgecumbe Summers ◽  
Mark A. Wall ◽  
Mukul Kumar ◽  
Steven J. Matthews ◽  
Raú B. Rebak
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Grain Boundaries ◽  
Phase Stability ◽  
Charpy Impact ◽  
Uniform Thickness ◽  
Annealed Condition ◽  
Charpy Impact Toughness ◽  
Transmission Electron ◽  
Carbide Particles

AbstractThe phase stability of C-22 alloy (UNS #N06022) was studied by aging samples at 593, 649, 704 and 760°C for 2000 h (2.7 mo) and 16,000 h (1.8 yr). The tensile properties and the Charpy impact toughness of these samples were measured in the mill annealed condition as well as after aging. The microstructures of samples aged 16,000 hours were examined using scanning and transmission electron microscopy (SEM and TEM). Preliminary TEM results suggest that μse forms at all temperatures investigated. Discrete carbide particles in addition to a film with very uniform thickness which appears to be μ phase formed on grain boundaries in the sample aged at 593°C. The ordered Ni2(Cr, Mo) phase was also seen in this sample. At the higher aging temperatures, mainly μ phase forms covering all the grain boundaries and also distributed throughout the bulk. Although strength increased somewhat with aging. the ductility decreased due to the formation of these grain boundary precipitates and brittle intermetallics.

The Influence of the ECAP Temperature on Microstructure and Mechanical Properties of a Magnesium Alloy

2006 ◽  
Vol 503-504 ◽  
pp. 609-614 ◽  
Author(s):  
Olya B. Kulyasova ◽  
Rinat K. Islamgaliev ◽  
Nikolay A. Krasilnikov
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Thermal Stability ◽  
Transmission Electron Microscopy ◽  
Magnesium Alloy ◽  
Volume Fraction ◽  
Angular Pressing ◽  
Transmission Electron ◽  
Significant Difference ◽  
Thermal Stability Of

The influence of the equal channel angular pressing (ECAP) temperature (150-350oC) on microstructure of the AM60 magnesium alloy has been investigated using transmission electron microscopy. It was demonstrated that application of various ECAP regimes leads to significant difference in a grain size and volume fraction of precipitates in investigated material. Thermal stability of precipitates and correlation between microstructure and tensile strength are discussed.

Effects of Shrinkage Porosity on Mechanical Properties of a Sand Cast Mg-Y-Re (WE54) Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 390-397 ◽  
Author(s):  
Ji Lin Li ◽  
Yue Qun Ma ◽  
Rong Shi Chen ◽  
Wei Ke
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Grain Boundaries ◽  
Volume Fraction ◽  
Strengthening Effect ◽  
Secondary Phases ◽  
Sand Cast ◽  
Microstructure Observation ◽  
Porosity Volume Fraction

The distribution of shrinkage porosities in sand cast Mg-Y-RE (WE54) alloy castings was characterized through density measurement and calculated by Archimedess principle. The effect of porosity on mechanical properties of sand cast WE54 alloy was investigated through tensile tests and microstructure observation. It was found that the shrinkage porosities distributed mainly in the middle of the plate where the liquid feeding was quite inconvenient. And the porosities were formed along grain boundaries when secondary phases formed at the end of solidification. Hardness tests showed that the vikers hardness declined linearly with increasing porosity volume fraction. While the tensile strength and nominal yield strength declined exponentially as the porosity volume fraction increased. Microstructure observation showed that the fracture cracks propagated along the grain boundaries where porosities and secondary phases gathering together in as-cast WE54 alloy. The tiny porosities distributed in the secondary phases were observed, which could reduce the tensile strength of cast specimens significantly. The heat treatment strengthening effects were significantly weakened by porosities, and even no heat treatment strengthening effect was detected when the porosity volume fraction was higher than 1%. The microstructure observation also proved that no heat treatment strengthening effect existed in samples containing porosities.

Effects of Impulse Current on Mechanical Behavior of Ti and Ta

2013 ◽  
Vol 763 ◽  
pp. 97-101
Author(s):  
Yao Li ◽  
Jun Jie Yang ◽  
Ping Xue ◽  
Wu Xin Yu ◽  
Zhi Jiang Zuo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Slip Systems ◽  
Apparent Effect ◽  
Bcc Metals ◽  
Transmission Electron ◽  
Pure Metals ◽  
Impulse Current

In this paper, pure metals Ti and Ta were used to study the effects of impulse current on their mechanical properties. The results showed that the impulse current caused the tensile strength of the two metals to decline remarkably. The elongation of metal Ta rose and was enhanced with increasing current density. But as for metal Ti, the elongation hardly rose. Theoretical analysis suggested that the impulse current had little apparent effect on HCP metals, for it had less slip systems; however, it had obvious effects on the elongation of BCC metals, for they had more potential slip systems. The transmission electron microscopy (TEM) observations showed that crystal microstructure of the two metals had not changed significantly.

Effect of Heat-Treatment on the Mechanical Properties of TiB2P/2024Al Composite

2007 ◽  
Vol 353-358 ◽  
pp. 1322-1325
Author(s):  
Long Tao Jiang ◽  
Min Zhao ◽  
Rui Jun Fan ◽  
Shao Lei Xu ◽  
De Zhi Zhu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Squeeze Casting ◽  
Hardness Measurement ◽  
Obvious Effect ◽  
Casting Technology ◽  
Transmission Electron ◽  
Peak Aged

55vol% TiB2P/2024Al composite was fabricated by squeeze casting technology, and the effect of heat treatment on mechanical properties of the composites was studied by means of hardness measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile testing etc. Results show that heat treatment has remarkable influence on the hardness and the tensile strength of the composites. For TiB2P/2024Al composites, the composites aged at 130°C for 5h can obtain the highest hardness, and the composites peak-aged at 160°C and aged at 190°C for 24h can obtain the higher tensile strength, which is due to the type of precipitates in the composites. Considering the experimental error, heat treatments has no obvious effect on elastic modulus of the experimental composite.

Microstructure and Mechanical Properties of Mg-9Al-6.5Ca-3Zn-0.6Mn-XNd Alloys Prepared by Spray Forming

2011 ◽  
Vol 117-119 ◽  
pp. 1447-1452
Author(s):  
Guo Wei Zhang ◽  
Zheng Chen ◽  
Wei Chen ◽  
Hai Ying Xin ◽  
Jing Zhai ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Scanning Electron Microscopy ◽  
Spray Forming ◽  
Protective Atmosphere ◽  
Forming Technology ◽  
Microstructure And Mechanical Properties ◽  
Transmission Electron ◽  
Scanning Electron

The Mg-9Al-3Zn-0.6Mn-xNd alloys, preformed with φ300mm size, has been prepared by spray forming technology under a protective atmosphere. The microstructure and mechanical properties have been investigated by XRD, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and strengths tested mechine. As a result, the precipitate phases in the alloys were the finest when the Nd content was 1% compared the alloys with the Nd content were 2% and 3%, the size of precipitation phases are between 1-2um and there are phases like Mg2Ca，Al2Ca，and MgZn2in the alloys. After extrusion, recrystallization microstructures were found in the alloys. The tensile strengths are between 400-450MPa and the yield strengths are between 350-370MPa respectively as the differences content of Nd in the alloys after heat treatment.

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