Procedure

Parameter Analysis and Porosity Reduction of Thin Film TiB2+AlMgB14 Direct Laser Deposition on 1095 Steel Tracks

Mackenzie J. Ridley (Berea College)Faculty Advisers: Dr. William Cross, Dr. Michael West, Dr. Alfred Boysen

South Dakota School of Mines and TechnologyBack to the Future Undergraduate Research Program, Summer 2016

Thank you to the National Science Foundation for providing opportunity for excellent research at SDSM&T.Grant NSF #DMR-1460912

SEM and EDS Analysis• Pore main compositions – Oxygen,

Aluminum, Carbon• Uniform mixture of TiB2+AlMgB14, Inconel

625 Nickel alloy, and 1095 steel

• Martensite region visible• Uniformity - Iron and Titanium found

evenly distributed• Discrepancy - Nickel deposited near

surface

IntroductionMany of today’s industrial abrasives, blades, and cutting tools are protected by thin layers of alloyed materials in order to increase efficiency and reduce wear. This study will look at the addition of thin film TiB2+AlMgB14, a ceramic alloy referred to as BAM, on thin 1095 high carbon steel tracks as a model for industrial tools. Under correct conditions, BAM is classified as a superhard alloy with a unique coefficient of friction of 0.04 (slicker than Teflon). Processing parameters of TiB2+AlMgB14, namely laser power, will be analyzed to provide suitable constraints to minimize porosity and increase hardness, strength, and longevity of the applied steel tracks.The goal of this project is to optimize processing

parameters of Direct Laser Deposition by minimizing porosity within TiB2+AlMgB14 thin films through x-ray micro-ct, microhardness

testing, spectroscopy, and microscopy analyses.

Hypotheses

ConclusionsIncreases in laser power of direct laser deposition demonstrate various changes in levels of porosity and microhardness within the deposited region. For the studied range (88.0 – 179.0 Watts) a laser power of 118.0 Watts proved most effective in minimizing gas and powder porosity within the deposited BAM region. This setting also proved to have the second highest microhardness from the surface and through the Martensite region, behind Sample 4 (133.0 Watts). Hardness testing and density analysis from x-ray attenuation points to Sample 4 (133.0 Watts) as the deposition with the least porosity percentage, although this conflicts with the Avizo Imaging Software. Powder porosity occurred in samples of lower laser power, although gas pores dominated all clad regions of the studied samples. Sample 2 (103.0 Watts) did not receive a uniform deposition layer, and hence may provide inaccurate data.

Xradia Micro-CT 400 Density Analysis

• Determine uniformity between sample depositions

• Scaling of normalized x-ray attenuation data

• True BAM Density: 3.14 g/cm3

• Goal: Uniform sampling

Avizo Software Porosity Extraction

• Porosity separated from clad region• Total volume fraction analyzed for

comparison

Buehler Micromet 4 Microhardness Testing

• Vertical testing from surface through BAM transition region

• Transition region - Martensite formation

Reconstruction Artifacts• Artifacts Found

• Streaks, shading, rings, ghosting effect of overlapping images

• Beam Hardening Coefficient: 0.3 – 1.3• Center Shift: 69 micron per pixel

Left: 3D Render of Found Artifacts, Top Right: Cross-section of Deposition

Artifacts, Bottom Left: Internal Ring Artifacts

• Porosity will decrease with an increase in laser power

• Porosity will originate more from gas pores, rather than from trapped sections of powder alloy

• Porosity will decrease with an increase in microhardness in the clad region

• Multi-layer depositions will have less porosity than those of a single layer deposition of materialMaterial

Powder Particle Size

(Micron)Melting Point (°C) Microhardness

GPaDensity (g/cm3)

Powder Proportions

TiB2+AlMgB

14 44 – 106 TiB

2 (2970)

AlMgB14

(2000)

28 - 46 3.14 80%

Inconel 625 Nickel 44 – 106 1290 - 1350 13 - 24 8.44 20%

1095 Steel N/A 1515 3.03 7.87 N/A

Future Work• Vacuum seal direct laser deposition chamber• Direct laser deposition beam alignment • Adjust other processing parameters, such as

deposition speed, powder flow rate, and powder application angle

• Failure Analysis of TiB2+AlMgB14 depositions• Compare results with multi-layer depositions

Steel

BAM

AirBakeLite

500 um

Top Left: 3D Render with Artifacts Removed,Top Middle: 3D Opaque Render with Porosity Separation,

Bottom Left: Clad Region Internal Porosity,Right: Translucent Clad Region Porosity

DLD Laser Power (Watts)

Porosity Volume (mm3)

Total Volume (mm3)

Total Porosity

%

Porosity %

From Calculat

ed Density

Mean Pore

Radius (Micron

s)

88.0 1.06E+07

1.11E+09 0.957 0.91 37.84

103.0* 1.25E+07

1.47E+09 0.850 1.14 18.82

118.0 7.59E+06

1.25E+09 0.605 0.63 30.45

133.0 1.26E+07

1.35E+09 0.928 0.39 25.85

149.0 1.81E+07

1.37E+09 1.326 0.89 27.53

164.0 1.26E+07

1.17E+09 1.077 0.90 30.81

179.0* 7.61E+06

2.04E+09 0.374 0.91 21.14

500 um

Spectrum 1

Atomic %

Spectrum 2

Atomic %

Spectrum 4

Atomic %

C 13.67 C 24.0

1 C 24.30

O 52.22 Si 0.79 B 51.6

2

Fe 0.90 Fe 50.75 Fe 0.57

Cr 0.14 Cr 3.83 Cr 0.09Ca 0.22 Mo 2.04 W 0.30

Ti 7.44 Ti 7.12 Ti 23.13

Al 20.48 Nb 2.20 ## ##

Mg 4.91 Ni 9.25 ## ##

Total 100.00 Total 100.

00 Total 100.00

TiB2+AlMgB14 Surface EDS analysis, Magnification 1040 X, EHT = 15 KV

TiB2+AlMgB14 Surface EDS analysis, Magnification 110 X, EHT = 15 KV Left: SEM Image,Left Middle: EDS Iron Concentration, Right Middle: EDS Nickel Concentration

Right: EDS Titanium Concentration

• VDK 3000 Direct Laser Deposition• Equipment repair• Creation of unique parts• Precision placement of materials• Cost efficient and effective method to hard

coatings, such as diamond• TiB2+AlMgB14

• High microhardness• Low coefficient of friction• Low coefficient of thermal expansion

• Porosity• Parameters: Laser power, deposition speed,

powder flow rate, powder application angle, gas flow rate, surrounding atmosphere

Sample Laser Power

(Watts)

Experimental Density g/cm3

Air BAM Steel88.0 0 3.112 7.87

103.0 0 3.104 7.87118.0 0 3.120 7.87133.0 0 3.128 7.87149.0 0 3.112 7.87164.0 0 3.112 7.87179.0 0 3.111 7.50

500 um

500 um

0 20 40 60 80 100 120275

350

425

500

575

650

725

800

875

950

88.0 Watts

103.0 Watts

118.0 Watts

133.0 Watts

149.0 Watts

164.0 Watts

179.0 Watts

Distance From Top of TiB2+AlMgB14 Deposition (microns)

HV

500 um

* Sample Analysis may not be accurate due to curvature in the steel tracks before deposition

88 103 118 133 148 163 178 1930.000

0.200

0.400

0.600

0.800

1.000

1.200

1.400

0.957

0.997

0.605

0.928

1.326

1.077

0.374

Total Percent Volume of Porosity in Single Layer Deposition of TiB2+AlMgB14 for Varied Laser

Powers

Avizo Calcu-lated Poros-ity Density Calculated Porosity

Laser Power (Watts)

Poro

sity

Per

cent

age