Effect of Heat Treatment on the As-Cast Microstructure and Hardness of NiSi3B2 Alloy

Cast Ni-Si-B alloys have the potential for high-temperature applications because of their high resistance to wear, impact, corrosion, and oxidation at elevated temperatures due to an appropriate balance of hard phases and austenite that ensures a good compromise between toughness and hardness. In this work, NiSi3B2 specimens, fabricated by the lost-wax casting process, were investigated. Given the complex multiphase cast microstructure, a differential scanning calorimeter (DSC-TGA) analysis was employed to characterize the reactions that occur during solidification and the resulting phases were characterized using scanning electron microscopy (SEM), with energy-dispersive microanalysis (EDS) and backscattered electron (BSE) image and X-ray diffraction (XRD). Due to the presence of hard phases, machining of the Ni-Si-B components can pose additional difficulties. Therefore, the conditions of the solution heat treatment, which might lead to the homogenization of the microstructure, consequently improving its machinability, were also investigated. The results of the heat-treated samples indicated that the dissolution of the eutectic constituent is accompanied by a significant decrease in the hardness (approximately 17%). It is important to emphasize that the solution heat treatments carried out reduced the hardness without affecting the percentage of borides, which will allow improving the machinability without adversely affecting the alloy performance in service.

Download Full-text

EFFECTS OF HEAT TREATMENT ON TRIBOLOGICAL BEHAVIOR OF ELECTROLESS Ni–B COATING AT ELEVATED TEMPERATURES

Surface Review and Letters ◽

10.1142/s0218625x18500142 ◽

2017 ◽

Vol 24 (Supp01) ◽

pp. 1850014 ◽

Cited By ~ 13

Author(s):

ARKADEB MUKHOPADHYAY ◽

TAPAN KUMAR BARMAN ◽

PRASANTA SAHOO

Keyword(s):

Heat Treatment ◽

Elevated Temperatures ◽

Tribological Behavior ◽

Wear Behavior ◽

X Ray Diffraction ◽

X Ray ◽

Heat Treated ◽

Pin On Disc ◽

Mixed Layers ◽

Electroless Ni

The present work investigates the effects of heat treatment on friction and wear behavior of electroless Ni–B coatings at elevated temperatures. Coating is deposited on AISI 1040 steel specimens and subjected to heat treatments at 350[Formula: see text]C, 400[Formula: see text]C and 450[Formula: see text]C. Coating characterization is done using scanning electron microscope, energy dispersive X-Ray analysis and X-Ray diffraction analysis. Improvement in microhardness is observed for the heat treated deposits. Further, the effect of heat treatment on the tribological behavior of the coatings at room temperature, 100[Formula: see text]C, 300[Formula: see text]C and 500[Formula: see text]C are analyzed on a pin-on-disc setup. Heat treatment at 350[Formula: see text]C causes a significant improvement in the tribological behavior at elevated temperatures. Higher heat treatment temperatures cause deterioration in the wear resistance and coefficient of friction. The wear mechanism at 100[Formula: see text]C is observed to be predominantly adhesive along with abrasion. While at 300[Formula: see text]C, abrasive wear is seen to be the governing wear phenomenon. Formation of mechanically mixed layers is noticed at both the test temperatures of 100[Formula: see text]C and 300[Formula: see text]C for the coatings heat treated at 400[Formula: see text]C and 450[Formula: see text]C test temperature. The predominant wear mechanisms at 500[Formula: see text]C are abrasive and fatigue for as-deposited and heat treated coatings, respectively.

Download Full-text

Evaluation of Dislocation Densities in Various Microstructures of Additively Manufactured Ti6Al4V (Eli) by the Method of X-ray Diffraction

Materials ◽

10.3390/ma13235355 ◽

2020 ◽

Vol 13 (23) ◽

pp. 5355

Author(s):

Amos Muiruri ◽

Maina Maringa ◽

Willie du Preez

Keyword(s):

Heat Treatment ◽

Elevated Temperatures ◽

Direct Metal Laser Sintering ◽

X Ray Diffraction ◽

Flow Properties ◽

X Ray ◽

Heat Treated ◽

Dislocation Densities ◽

Stress Relieving ◽

As Stress

Dislocations play a central role in determining strength and flow properties of metals and alloys. Diffusionless phase transformation of β→α in Ti6Al4V during the Direct Metal Laser Sintering (DMLS) process produces martensitic microstructures with high dislocation densities. However, heat treatment, such as stress relieving and annealing, can be applied to reduce the volume of these dislocations. In the present study, an analysis of the X-ray diffraction (XRD) profiles of the non-heat-treated and heat-treated microstructures of DMLS Ti6Al4V(ELI) was carried out to determine the level of defects in these microstructures. The modified Williamson–Hall and modified Warren–Averbach methods of analysis were used to evaluate the dislocation densities in these microstructures. The results obtained showed a 73% reduction of dislocation density in DMLS Ti6Al4V(ELI) upon stress relieving heat treatment. The density of dislocations further declined in microstructures that were annealed at elevated temperatures, with the microstructures that were heat-treated just below the β→α recording the lowest dislocation densities.

Download Full-text

Hardening of Selective Laser Melted M2 Steel

10.31399/asm.cp.ht2021p0007 ◽

2021 ◽

Author(s):

Mei Yang ◽

Yishu Zhang ◽

Haoxing You ◽

Richard Smith ◽

Richard D. Sisson

Keyword(s):

Heat Treatment ◽

High Speed ◽

Cutting Tools ◽

High Speed Steel ◽

High Hardness ◽

Steel Part ◽

X Ray Diffraction ◽

X Ray ◽

Heat Treated ◽

Near Net Shape

Abstract Selective laser melting (SLM) is an additive manufacturing technique that can be used to make the near-net-shape metal parts. M2 is a high-speed steel widely used in cutting tools, which is due to its high hardness of this steel. Conventionally, the hardening heat treatment process, including quenching and tempering, is conducted to achieve the high hardness for M2 wrought parts. It was debated if the hardening is needed for additively manufactured M2 parts. In the present work, the M2 steel part is fabricated by SLM. It is found that the hardness of as-fabricated M2 SLM parts is much lower than the hardened M2 wrought parts. The characterization was conducted including X-ray diffraction (XRD), optical microscopy, Scanning Electron Microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) to investigate the microstructure evolution of as-fabricated, quenched, and tempered M2 SLM part. The M2 wrought part was heat-treated simultaneously with the SLM part for comparison. It was found the hardness of M2 SLM part after heat treatment is increased and comparable to the wrought part. Both quenched and tempered M2 SLM and wrought parts have the same microstructure, while the size of the carbides in the wrought part is larger than that in the SLM part.

Download Full-text

EFFECT OF HEAT TREATMENT ON MICROSTRUCTURE AND CORROSION RESISTANCE OF Ni-B-W-Mo COATING DEPOSITED BY ELECTROLESS METHOD

Surface Review and Letters ◽

10.1142/s0218625x19500239 ◽

2018 ◽

Vol 25 (08) ◽

pp. 1950023 ◽

Cited By ~ 6

Author(s):

ARKADEB MUKHOPADHYAY ◽

TAPAN KUMAR BARMAN ◽

PRASANTA SAHOO

Keyword(s):

Heat Treatment ◽

Corrosion Resistance ◽

Electrochemical Techniques ◽

Sodium Molybdate ◽

Medium Carbon Steel ◽

X Ray Diffraction ◽

X Ray ◽

Solid Solution Strengthening ◽

Heat Treated ◽

Electroless Coatings

The present work reports the deposition of a quaternary Ni-B-W-Mo coating on AISI 1040 medium carbon steel and its characterization. Quaternary deposits are obtained by suitably modifying existing electroless Ni-B bath. Composition of the as-deposited coating is analyzed by energy dispersive X-ray spectroscopy. The structural aspects of the as-deposited and coatings heat treated at 300[Formula: see text]C, 350[Formula: see text]C, 400[Formula: see text]C, 450[Formula: see text]C and 500[Formula: see text]C are determined using X-ray diffraction technique. Surface of the as-deposited and heat-treated coatings is examined using a scanning electron microscope. Very high W deposition could be observed when sodium molybdate is present in the borohydride-based bath along with sodium tungstate. The coatings in their as-deposited condition are amorphous while crystallization takes place on heat treatment. A nodulated surface morphology of the deposits is also observed. Vickers’ microhardness and crystallite size measurement reveal inclusion of W and Mo results in enhanced thermal stability of the coatings. Solid solution strengthening of the electroless coatings by W and Mo is also observed. The applicability of kinetic strength theory to the hardening of the coatings on heat treatment is also investigated. Corrosion resistance of Ni-B-W-Mo coatings and effect of heat treatment on the same are also determined by electrochemical techniques.

Download Full-text

Preparation and Assessment of Heat-Treated α-Chitin Nanowhiskers Reinforced Poly(viny alcohol) Film for Packaging Application

Materials ◽

10.3390/ma11101883 ◽

2018 ◽

Vol 11 (10) ◽

pp. 1883 ◽

Cited By ~ 7

Author(s):

Chao Peng ◽

Guangxue Chen

Keyword(s):

Heat Treatment ◽

Composite Films ◽

Barrier Properties ◽

Mechanical Tests ◽

Light Transmittance ◽

Poly Vinyl Alcohol ◽

X Ray Diffraction ◽

X Ray ◽

Heat Treated ◽

Chitin Nanowhiskers

In this study, poly(vinyl alcohol) (PVA) composite films enhanced by α-chitin nanowhiskers (ChWs) were prepared through heat treatment. The obtained membranes were assessed by means of FTIR spectroscopy, X-ray diffraction, thermogravimetric analysis, regular light transmittance, mechanical tests, permeability and water absorption. The influence of the nano-component and heat treatment on the mechanical, thermal and water-resistant properties of the composite membrane were analyzed. From the results of the work, the produced films with excellent barrier properties and inexpensive raw processed materials have great prospects in packaging applications.

Download Full-text

Magnetization and XRD Studies of Laser Heat Treated SmCo5 Powders

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1016.1299 ◽

2021 ◽

Vol 1016 ◽

pp. 1299-1304

Author(s):

Naidu Seetala ◽

Deidre Henderson ◽

Jumel Jno-Baptiste ◽

Hao Wen ◽

Sheng Min Guo

Keyword(s):

Heat Treatment ◽

Hydrogen Gas ◽

Vacuum Furnace ◽

X Ray Diffraction ◽

X Ray ◽

Micro Particles ◽

Laser Heat ◽

Heat Treated ◽

Xrd Studies ◽

Hydride Phases

The microstructure and magnetization of SmCo5 micro-particles may be used as feedstock for 3D printing to make miniature strong magnets. Thus, the magnetic response and microstructures of commercially available SmCo5 micro-particles were studied under various heat treatments using a high wattage laser. The magnetization of laser heat treated powders at 50-watt showed an increase in magnetization, while the 75-watt melt showed a little to no change. Unfortunately, the coercivity of both laser heat treated samples decreased significantly. Oxidation during the heat treatment is suspected to result in low coercivity. Purging with argon-gas prior to laser heating showed improved coercivity. To further minimize the oxidation problem a set of SmCo5 powder was reduced prior to laser heat treatment using a constant flow of hydrogen gas while being heated at various temperatures from 100 oC to 400 oC for a period of ~4 hours. The results show that the magnetization generally increases with the temperature, while the coercivity decreases significantly. Another set of SmCo5 was annealed in a vacuum furnace for one hour at temperatures between 200 oC and 400 oC in order to confirm that no hydride phases were formed during reduction. The magnetization and coercivity showed similar variations with annealing temperature to those for the reduced powders confirming that these variations may be due to change in crystal structure rather than formation of hydrides. X-ray Diffraction (XRD) studies were performed to identify the changes in crystal phases.

Download Full-text

Copper(I) Halide Nanoparticle-dispersed Glasses Prepared by Copper Staining

Journal of Materials Research ◽

10.1557/jmr.2005.0295 ◽

2005 ◽

Vol 20 (9) ◽

pp. 2480-2485 ◽

Cited By ~ 4

Author(s):

Kohei Kadono ◽

Tatsuya Suetsugu ◽

Takeshi Ohtani ◽

Toshihiko Einishi ◽

Takashi Tarumi ◽

...

Keyword(s):

Electron Microscopy ◽

Heat Treatment ◽

Surface Region ◽

Borosilicate Glasses ◽

X Ray Diffraction ◽

X Ray ◽

Depth Profiles ◽

Transmission Electron ◽

Heat Treated ◽

Glass Heat

Copper(I) chloride and bromide nanoparticle-dispersed glasses were prepared by means of a conventional copper staining. The staining was performed by the following process: copper stain was applied on the surfaces of Cl−- or Br−-ion-containing borosilicate glasses, and the glasses were heat-treated at 510 °C for various times. Typical exciton bands observed in the absorption spectra of the glasses after the heat treatment indicated that CuCl and CuBr particles were formed in the surface region of the glasses. The average sizes of the CuCl and CuBr particles in the glasses heat-treated for 48 h were estimated at 4.8 and 2.7 nm, respectively. The nanoparticles were also characterized by x-ray diffraction and transmission electron microscopy. Depth profiles of Cu and CuBr concentration in the glass heat-treated for 48 h were measured. Copper decreased in concentration monotonously with depth, reaching up to 60 μm, while the CuBr concentration had a maximum at about 25 μm in depth.

Download Full-text

Microstructure and Creep Properties of Casting Mg-8Al-0.3Mn Alloy Containing Ca and Sr

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.1386 ◽

2011 ◽

Vol 189-193 ◽

pp. 1386-1392

Author(s):

Yan Lou ◽

Luo Xing Li

Keyword(s):

Grain Boundaries ◽

Creep Resistance ◽

Elevated Temperatures ◽

Secondary Phases ◽

X Ray Diffraction ◽

Creep Tests ◽

Creep Properties ◽

Calcium Addition ◽

Order Of Magnitude ◽

Cast Microstructure

Microstructures and creep properties of AM80 alloy with calcium and strontium additions have been investigated by using OM, X-ray diffraction, SEM and creep tests. The results indicate that the as-cast microstructure of the AM80 alloy consists of the α-Mg matrix, bones-shaped Mg17Al12 and lamellar second precipitation phase at grain boundaries. Calcium and strontium can refine the grain size and the secondary phases. Calcium addition results in the formation of a fishbone Al2Ca eutectic phase in AM80 alloy. With the increase of calcium, reticular Al2Ca phase distribute at the grain boundaries. The creep resistance of the AM80 alloy is significantly improved by a small amount of strontium and calcium addition due to the formation of a grain boundary network consisting of the high melting point Al2Ca phase. Microstructure observations performed on the sample after creep testing reveal that the phase is distorted during creep, reflecting its formation in the as-cast microstructure is unbeneficial to creep properties of the AM80 alloy. The creep resistance of the alloy at elevated temperatures was remarkably increased when calcium was added combined with strontium. The highest creep resistance was obtained from the alloy with xSr and y3Ca addition and its steady state creep rate reached as low as 3.941×10-8s-1, one order of magnitude lower than that of alloy AM80 without strontium and calcium additions.

Download Full-text

OPTIMIZATION of DYNAMIC CH4 GAS HEAT TREATMENT OF NANOCRYSTALLINE STRONTIUM HEXAFERRITE

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194512002711 ◽

2012 ◽

Vol 05 ◽

pp. 752-759 ◽

Cited By ~ 1

Author(s):

R. DEHGHAN ◽

S. A. SEYYED EBRAHIMI ◽

H. R. KOOHDAR

Keyword(s):

Heat Treatment ◽

Phase Composition ◽

Strontium Hexaferrite ◽

Gas Flows ◽

Optimum Conditions ◽

X Ray Diffraction ◽

Heating And Cooling ◽

Heat Treated ◽

Size And Morphology ◽

Magnetic Nature

In this research the influence of dynamic CH 4 heat treatment on Sr -hexaferrite has been investigated. With the gas heat treatment, the phase composition, particles size and the morphology of Sr -hexaferrite change significantly. Due to this, the hard magnetic nature of the material changes from hard to soft. The strontium hexaferrite powder was prepared by conventional route with calcination of the mixture of strontium carbonate and hematite at 1100°C for 1 hour. Then the resultant Sr -hexaferrite was isothermally heat treated in methane dynamic atmosphere at various temperatures and gas flows for different times. The rate of heating and cooling were 10°C/min. The optimum conditions were obtained at 950°C and 15CC/min flow for 0.5 hour. The effects of gas heat treatment on the phase composition and the particles size and morphology were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibration Sample Magnetometery (VSM) techniques. The results show the decomposition of Sr -hexaferrite and reduction of the resultant hematite mainly to iron. The crystallite size of the resultant iron was also measured below 50nm.

Download Full-text

The Effect of Oxygen on Heat Treatment Behavior of Titanium-50mass%Tantalum-5mass%Zirconium Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.539-543.3613 ◽

2007 ◽

Vol 539-543 ◽

pp. 3613-3618

Author(s):

Masahiko Ikeda ◽

Masaaki Mori

Keyword(s):

Heat Treatment ◽

Shape Memory ◽

Shape Recovery ◽

Liquid Nitrogen Temperature ◽

X Ray Diffraction ◽

Resistivity Ratio ◽

Orthorhombic Martensite ◽

Β Phase ◽

Heat Treated ◽

Effect Of Oxygen

To develop new shape memory and super-elastic alloys for medical applications, titanium alloys using non-toxic metallic elements, such as Ta and Nb, are being actively investigated. In this study, aimed at developing new shape memory Ti alloys, we investigate the effect of oxygen, a powerful alpha stabilizing interstitial element, on the heat treatment behavior of Ti-50mass%Ta-5mass%Zr through electrical resistivity and Vickers hardness measurements and shape-recovery tests. Ti-50Ta-5Zr-0.14Ox and 0.33Ox alloys, and the β and α” bi-phase was confirmed by XRD. Only the β phase was identified in the Ti-50Ta-5Zr-0.62Ox alloy. Upon isochronal heat treatment, the resistivity at LN and resistivity ratio of Zr-0.33 and 0.62Ox alloys decreased up to around 523 K. In the 5Zr-0.62Ox alloy, orthorhombic martensite and the α” and β phases were identified in the specimens heat-treated at 473 and 523 K. The decreases in resistivity at liquid nitrogen temperature and resistivity ratio are due to the formation of α” during isochronal heat treatment. The formation of α” was confirmed by X-ray diffraction in the 5Zr-0.62Ox alloy. The shape memory effect was observed in 5Zr-0.14 and 0.33Ox alloys and the shape recovery ratio of both alloys was about 40% at 673 K.

Download Full-text