High Pressure-High Temperature

Processing of Advanced Materials

Vitali F. Nesterenko

Department of Mechanical and Aerospace Engineering

Materials Science and Engineering Program

University of California, San Diego

High Pressure-High Temperature Processing:

Areas of Application and Examples

• Parts/products which are impossible to process

at lower temperatures

• Parts/products which must have excellent

mechanical and physical properties

• Ballistic grade Ti alloy based composites

• Bulk superconducting magnesium diboride discs and

coils

• High strength, high density, highly ordered Al-W fiber

composite tubes

High Pressure-temperature

Equipment at UC San Diego

• HIP and CIP units: 2 kbar, 2000°C

• Pressure and temperature are independently

controlled

Sample diameter up to 40 mm, height up to 100 mm

Ballistic-grade Ti Alloy-based Composites

Atomized T6-4

Powder used for

HIPing

Vacuum Sealed T6-4 Powder in Pyrex Glass Capsule

(left), HIPed Sample, Glass capsule removed (right)

Collaborators

processing, static and dynamic properties:YaBei Gu and SastryIndrakanti (UCSD);

ballistic testing: W long rod penetrator -Singh Brar (University of Dayton Research Institute, Dayton, Ohio); Projectiles with different shapes - Werner Goldsmith (UC Berkeley)

Geometry of HIPed Ti6-4 Composites with

Embedded Alumina Tubes and Rods

• To deflect projectile at early penetration stage

• Activate ‘horizontal’ damage and prevent penetration

• Introduce new channel of energy dissipation through comminution

of covalent ceramics in cavity

• Replace vertical shear banding resulting in plug formation by

complex, volume distributed, highly heterogeneous pattern of

damage initiated by cavities and their interaction

Isotropic Microstructure of HIPed Ti-6-4 versus

Anisotropic Baseline Military Grade MIL-T-

9047G

Isotropic fine lamellar

mictrostructure resulting from

HIPing of PREP-ELI-nonmilled

powder; coarse lamellar

mictrostructure corresponding to

PREP-ELI-milled powder.

Non-milled Milled

50 mm 50 mm50mm

Anisotropic microstructure of

baseline military grade MIL-

T-9047G material in the plane

parallel to the axis of bar with

elongated a grains in axial

direction and intergranular b.

Target Assembly of Samples for Flat-ended

Projectile Testing

Back Plate

Ti-6Al-4VStainless steel

10mm

40mm

38mm

140mm

12.72mm

Impact Velocity

~ 400 m/s

Stainless steel

Back Plate

10mm

Target Assembly of Samples for Conical

Projectile Testing

Back Plate

Ti-6Al-4V

Back Plate

Stainless steel 30mm

30mm

40mm

38mm

140mm

12.7mm

Impact Velocity

~ 1000 m/s

Stainless steel

Length=38mm

MIL-T-9047G

(top figures) and

HIPed (bottom)

Targets

Perforated by

Conical

Projectiles

5m

m

5m

m

5m

m

5m

m

Baseline material (a,b, top figures), Runs 18N and 19N,

respectively, and projectiles trapped inside powder-based

targets (bottom figures, c, d), Runs 21N and 22N, respectively

Long Rod Ballistic Test Configuration

Shape of Craters, Impact by Long W Rod

Penetrator

Post critical behavior in the explosively driven

TWC test with Ti-6Al-4V: baseline MIL-T-

9047G with localized damage (left); HIPed

with more uniformly distributed damage (right)

Performance of Ti6-4 HIPed samples

• Ballistic performance of baseline material (MIL-T-9047G) andHIPed texture free materials was compared under three types ofpenetration tests. HIPed materials as a rule demonstrate betterballistic performance in all three cases.

• Different crater shapes, absent of advanced shear cracks inHIPed materials and different shear band patterns wereobserved in baseline and HIPed materials.

• High gradient composite material were able to deflect long Wrod projectile, resulting in self-sealing of the crater due to thebuilt-in mechanism (fracture of alumina tubes).

• Post-critical behavior of the materials was evaluated byconducting hat-shaped specimen tests and thick wall cylinder(TWC) tests. HIPed materials demonstrate a comparable flowstress as the baseline material, but revealed essentially differentbehavior in TWC test - complex shear band pattern and shapeof the void.

HIPing of Bulk Magnesium Diboride, Assembling

Sample for High Pressure-temperature Processing

(MgB2 is impossible to sinter)

Sealed glass

capsuleMgB2

Pressure

transmitted

media, vacuum

sealed

Ta foil (plus Zr

foil in some

runs)

Collaborators:• DRS, mechanical, elastic properties at normal T

(Y. Gu - UCSD), at low T (R. Schwarz, U. Harms, A.

Serquis – LANL).

• Superconducting properties:

• Bulk: (B. Maple, B. Taylor, N. Frederick, S. Li -

UCSD)

• Bulk and wires: (F.M. Mueller, D.E. Peterson, A.

Serquis, L. Civale, D. L. Hammon, X.Z. Liao, Y.T.

Zhu, M. Jaime, J.Y. Coulter, J.Y. Huang, J.O. Willis,

N.O. Moreno, J.D. Thompson, R.K. Schulze (LANL).

• Microwave properties (parallel plates): (A.

Findikoglu, A. Serquis, L. Civale, X.Z. Liao, Y.T.

Zhu,M. Hawley, F.M. Mueller - LANL

• Microwave properties (RF cavity): (T. Tajima, F.

Krawczyk, J. Liu, D. Nguyen, D. Schrage, A.

Serquis, A. Shapiro – LANL).

Bulk Magnesium Diboride Samples after

HIPing and Machining

Microwave performance of high-density bulk MgB2

processed at UC San Diego

Microwave effective surface resistance Rs at 10 GHz vs temperature of: oxygen-free-high-

conductivity Cu (straight line); polycrystalline (long-short dashed line) and biaxially textured

(rectangles)YBa2Cu3O7-d; coarse-polished (dotted line), fine-polished (dashed line), fine

polished and ion-milled (circles) bulk HIPed MgB2 , measured at microwave magnetic field

level Hrf of 0.2 Oe (small filled circles and rectangles), and 4 Oe ~(large unfilled circles and

rectangles) (APL, vol. 83, no.1, pp. 108-110, 2003).

Hot-Isostatic Pressing of Magnesium

Diboride Coils

High Accuracy Measurements of Elastic

Properties of HIPed Samples by

Resonance Ultrasound Spectroscopy

Method

Properties of HIPed Magnesium Diboride

• Hot Isostatically Pressed magnesium diboride has attractive combinations

of properties: high density, environmental robustness, reasonable

machinability, high value of elastic modulus with high level of quality factor

Q, and fracture toughness comparable to alumina. It is capable for scaling

of the sample sizes and for manufacturing of devices with complex shapes.

• Critical current, upper critical field and irreversibility field are among the

best reported for this material (bulk and wires).

• Improved field dependence of critical current is probably due to specific

microstructural features of this material (better connectivity of grains,

absence of pores and redistribution of nanosized MgO particles in the bulk

of MgB2 grains instead being concentrated at the boundaries).

• Microwave performance is encouraging, but microstructure refinement is

necessary for the reduction of Rs.

Processing and Mechanical Properties of Al-

W Composite Tubes with Highly Ordered W

Fibers in Two Directions (Axial and Hoop)Collaborators:

• Processing: Po-Hsun Chiu (UCSD)

• Testing: Po-Hsun Chiu, Kenneth S. Vecchio (UCSD)

Static Mechanical Properties of Al-W

Composite Tubes

Static Mechanical Properties of Al-W

Composite Tubes

• High density aluminum (Al)-tungsten (W) composite tubes with highly ordered periodic mesostructures of W fibers were processed using Cold Isostatic Pressing (CIPing) and Hot Isostatic Pressing (HIPing).

• Half of the specimens were additionally heat treated after HIPing to regain the properties of Al 6061-T6.

• The strength of both types of samples was investigated under quasistatic compression.

• Samples after additional heat treatment (HT) had higher microhardnessand increased the compressive strength to 600 MPa, and no reaction between W fibers and Al matrix was detected.

Dynamic Mechanical Testing of Al-W

Composite Tubes

• The split Hopkinson pressure bar was used to investigate the dynamic

behavior of high density aluminum alloy (Al 6061-T6) – tungsten (W) fibers

composite tubes with periodic arrangements of W fibers in axial and hoop

directions processed by using the combination of Cold Isostatic Pressing

(CIPing) and Hot Isostatic Pressing (HIPing).

• Additional heat treatment of some samples allowed them to regain the

original strength of Al 6061-T6, which was annealed during HIPing.

• The high-strain-rate deformation resulted in the strength increase for both

types of samples (with and without the heat treatment) compared to

quasistatic deformation.

• Samples after additional heat treatment exhibited higher dynamic strength.

• The strain rate sensitivity of the composite samples is caused by W fibers,

which are responsible for the high strength of the samples and mechanism

of their fracture.

Dynamic Mechanical Testing of Al-W

Composite Tubes

Future directions:

High pressure-temperature pressing

may answer challenges in additive

manufacturing of parts with complex

geometries

• Residual porosity

• Elongation to failure and ductility are low

• Complex thermal history, undesirable residual

stresses, anisotropy of microstructure

• The possible approach (probably the only one)

to improve mechanical properties of complex

AM 3-D structures is hot isostatic pressing