Injection moulding of water atomized stainless steel

Powder production MANUFACTURE SIZED

the effect of a capillary force in representing an internal intrinsic pressure and is extended by adding this to actual stress.

OF NANOMETRE

The model

POWDERS

Z. Junhui Metals,

(Research Beijing,

Inst. for Non-Ferrous

China).

PM

Technol.,

Vol 13, No 1, 1995, 48-56. (In Chinese.) Manufacturing processes for nanometre sized metal powders Emphasis is placed on

are reviewed. gas evaporation,

gas phase reaction mechanical alloying.

processes

and

OF

SHRINKAGE

191-195. In situ

monitoring

automatic

of

sintering

two

measurement

dimensions

of anisotropic

digital image processing

of

and

allows

shrinkage.

A new

algorithm

is used.

Results on die pressed carbonyl Ni, sintered at 13OO”C, are given. Shrinkage anomalies arising from die filling inhomogeneities friction

and

are identified.

Fundamentals STEREOLOGICAL

METHODS

I. Kohutek

al.

kove

Kosice,

(Slovak

Slovakia).

Metalurgie,

Stereology, description

No

which of

linking

S. Slim

of

Pokroky

Prm-

1995,

34-39.

l/2, is one

method

for

microstructures,

is

described. The method is used to show quantitative characterization possibilities, distribution in the

of particles plane of

microstructure. Computer models are compared with data for Al specimens

MODEL

Vol

France). 3,

effects of shot peening

in

strain cyclic loading,

It is reported predicted.

based

on

is described.

that residual stresses could be

The

X-ray

predictions

are compared

measurements

introduced

of

by shot peening.

or the

simulated experimental

(Inst.

et al.

Russia).

of Steels

Novye

Part 4, No

powder and

the

characteristics

sintering

composition 3 hours

in

and

Matere.

i 31.

amorphous

of &lO%Ni-lO%Y on

described.

Ar

of the

in formation

for

complete

was

sintering

phase

Milling

caused

AlaNi

Crystallization resulted

of

precipitated

for

5

amorphous

ALUMINIUM

CONSTITUTIVE POWDERS

E. Bauer, W. Wu (University Powder

of Technology,

Technol.,

Vol 85,

Reserve Metall.

and

temperature

stability

growth

of

structures effectively

at

described.

are

less

precipitates

results

are discussed

to the

and than

grain

Larger

high

precipitates.

described

pinning

high

The

is attributed

CraNb

are

precipitates

alloy with

conductivity

are

slow

No 9, 1995,2197-

The small nm

300

boundaries.

are about

1 urn. The

with regard

to Hall-

Petch and Orowan mechanisms.

and steel

STEEL

POWDERS

hours.

City,

Utah,

USA).

of Utah, Salt

Int.

J.

Powder

Metall., Vol 31, No 3, 1995, 247-256. A study intended to correlate the tensile strength

and density of HIP 304L stainless

steel, made from rapidly solidified is described.

Stress concentration

to pores is shown to be reduced deformation sharp

powders, effect due by tensile

due to plastic zone blunting

angled

interstices.

Measured

of

and

calculated strength/density curves are shown to differ by amounts which diminish as the density increases and particle shown

size decreases. HIP temperature is to be an important parameter

powder

for strength. INJECTION

MOULDING

OF

ATOMIZED

STAINLESS

of AlaY.

INFILTRATION

METAL

Western Ohio, USA).

of a Cu-8%Cr-4%Nb

strength

temperature

Lake

1, 1993,

conditions are

amorphization. during

effects

(Case

al.

Cleveland,

W. Kim, J.G. Byrne (University

(In Russian.) of

ALLOY

PROPERTIES OF HOT ISOSTATICALLY PRESSED RAPIDLY SOLIDIFIED

OF ALUMINIUMBY MECHANICAL

Mashin.,

Studies

et

STAINLESS

Moscow,

Teknol.

Ellis

Iron

residual

Aluminium

Alloys,

D.

University,

high

10, No

peening,

CHROMIUM-NIOBIUIM

2206. Studies

with 8% Al&a.

FOR COHESIVE

Graz, Austria).

Processes,

HIGH PERFORMANCE DISPERSION STRENGTHENED COPPER-

Mater. Trans. A, Vol26A,

MODELLING Paris,

of shot

PRESSURELESS A HYPOPLASTIC

x,

the fatigue life of parts is noted.

A simulation

stresses

size,

STRESSES

(ENSAM,

The beneficial

with

An equation,

USING

BEHAVIOUR

Mater. Man@ 1995, 579-588.

uniaxial

13,

size in 71

particle

OF RESIDUAL

et al.

extending

Fac-

Vol

density, y, is deduced.

Y. A. Skakow

Academy

(In English.)

such as inclusions

of W-Al is described.

measurements of pressure changes were made. The results are taken to show that atmospheric pressure is required and that capillarity may also contribute.

Copper

ALLOYING

FOR

OF MICROSTRUCTURES

et

Metal Process

study of particle

AMORPHIZATION NICKELYTTRIUM

DESCRIPTION

Sciences,

A statistical

MATERIAL

shrinkage, using digital image correlation, is described. The system provides non-

detection

(Non-Ferrous

DUE TO SHOT PEENING

Y. Mizuno et al. (Tohoku University, Sendai, Japan) Powder Metall., Vol 37, No 3, 1995,

in

L. Liguo

tory, Baoji, China. PM Technol., No 1, 1995, 31-33. (ln Chinese.)

PREDICTION

BY DIGITAL

CORRELATION

changes

OF MEAN POWDER

and sintered

SINTERING

with experiments.

PARTICLE SIZE ON SINTERED DENSITY OF TUNGSTEN-ALUMINIUM

samples

IN SITU MEASUREMENT

contact

INFLUENCE

y = 19.33-0.555x,

Sintering

IMAGE

is compared

or Al-12.5wt%Si, is described. It is shown that a pressure differential is required and

OF WATER STEEL

MATRIX

COMPOSITES

L. Cai, R.M. German

M.C. Flemings of Technology,

University, Pennsylvania, USA). fnt. J. PowderMetall., Vol 31, No 3, 1995, 257-264. Water atomized 316L stainless steel

et al. (Massachusetts Inst. Cambridge, USA). Metall.

(Pennsylvania

State

No 1, 1995, 1-9.

Mater. Trans. A, Vol 26A, No 8, 1995,2155-

powders

It is reported that a non-linear hypoplastic model had been applied to cohesive powders. The model incorporates

2159. Pressureless

shown to comply with the requirements for powder for MIM. A solids loading of 0.65

42

MPR April 1996

with additions

infiltration

of Sic preforms,

of Al, Ti and Ni by molten Al

and

was evaluated.

feedstock

mixing

Characteristics

proceedures

are

are

consolidation by extrusion is described. The structure is reported to be Al&a in a Mg rich matrix. Yield strength is 600 MPa and the specific yield strength is 3.3 MNm.kg-‘, which is higher than in commercial

Effects of process variables were determined. It is shown that contrarotation of electrode and roller gave the most effective production of powder.

Mg alloys.

Tungsten

THERMODYNAMIC ANALYSIS OF SILICONIZING OF STEEL PRODUCTS

Molybefenum

THROUGH

DAMAGE IN A TUNGSTEN COMPOSITE DUE TO DEBONDING AT TUNGSTEN-

SUPPRESSION

shown to be critical parameters. Variations of sintered properties were determined and results compared with gas atomized powders. There was greater shrinkage with the water atomized powder and high ductility despite a high oxide content.

A CHLORIDE

Y.G. Gurevich lurgiya,

Poroshkovaya

et al.

No 11/12,

1994,

sian.) Thermodynamics

readiliy

Metal-

25-27.

phase.

to siliconize

Below

chloridized

725°C

and

through

Si is more

transfer

of

Si

through the gaseous phase is apparent. As temperature increases chloridization of Fe increases. siliconizing

The results were process development

used in for iron

and steel parts. EFFECTOFCARBONON MICROSTRUCTURE OF ALLOY STEELS COOLED

AT MODERATE

(University

ham,

UK).

of Notting-

Powder

Vol 38, No 2, 1995, 141-146. It is reported that steel

Metall.,

had

been

made from mixed low and high steel powders with varying amounts The microstructures are described

alloy of C. with

regard

alloy

steel

to XC and powder

hardness increases

the low to high

ratio.

Phase

stability

and

were monitored. High %C the amount of retained austenite

and decreases INCREASE

phase stability.

IN FATIGUE

POWDER

FORGED

STRENGTH

CONNECTING

OF

RODS

D.A. Yeager et al. (Ford Motor Co, Dearborn, Michigan, USA). Powder Metall., Vol 38, No 3, 1995, 196-200. is

noted

increase by

that

the fatigue

the

shot

peening

strength

introduction

compressive 2%Cu Shot

of

a

surface

stress. This was quantified

steel,

in test

correlated peening

effect

of

can

of materials

a study of the effect of shot peening forms,

bar

with

was

peening

and

by on a

component

surface

stresses.

optimized in

TUNGSTEN

and

increasing

the

fatigue

GRAIN

Z. Lin, G. Bao Baltimore,

M.G.

Benz

et

(General

al.

Electric

Schenectady, New York, USA). Refiactorg Metals Hard Mater., No 6, 1995, 327-336. It is reported that increased temperatures,

in

rotating

Co,

Znt. J. Vol 13, operating

anode

X-ray

TiO in the emmisive coating. The problem is shown to be alleviated by placing a reactive

(Johns

USA).

boundaries

in

a Ni-Fe-W evolution,

and

applied

to reduce

the

activity of the C source.

of the

Titanium

flow.

COMPOSITES

S. Abkowitz

et al.

J. Metals, Vol 47, No 8,

1995, 40-41. Process development

and properties

low cost, high performance composites, based on lOvol%TiC, the

tensile

of

Ti alloy matrix Ti-6%A-4%V-

are described.

and

unreinforced

alloy,

is

reported.

is

deduced

element

of

and

methods.

progressive Predictions

damage are made

debonding

and

on

tensile

trends,

softening

strain due

to

are discussed.

STRUCTURE

STRENGTH

OF FRACTURE

Science

AND WORK

OF FIBROUS CERAMICS

Popovic

Research

et Inc,

al.

(Advanced

Tucson,

of

Ceramics

Arizona,

USA).

Vol 27, No 2, 1995,

oj’ Sin&ring,

127-133. Studies

structure

and

mechanical

FORMATION OF AMORPHOUS TITANIUM-SILICON ALLOY POWDERS

properties

AND SHOCK

ratio polycrystalline cells of Si,,N, separated by boundaries of BN. Materials with various

CONSOLIDATION

Y. Syono et al. (Tohoku University, Sendai, Japan). Mater. Science Engng A, A179/ A189 1994. It is reported

that ball milling of Ti-(20

to 50)at!%Si results in amorphization mean particle consolidation, partially

hardness

Annealing

and a

size of 20-30 nm. On shock of Ti-50%Si at 32.6 GPa, a

recrystallized

Vicker’s

structure

of

1300

was

with

a

obtained.

at 750°C caused recrystallization

and a hardness

increase

of

described.

SisN4-BN

The structures

architectures mechanically.

were

catastrophically flexure. The mapped

and

phenomena

ceramics

are

are high aspect

fabricated and All failed

tested non-

when tested in g-point mechanical behaviour is an

explanation

of

the

is given.

Electrical and magnetic materials

to 1700.

strength was confirmed.

CRYSTALLIZATION

CONDUCTIVITY

AND MAGNETIC PERMEABILITY OF AMORPHOUS IRON-BASED ALLOYS

PRODUCTION OF AMORPHOUS TITANIUM-COBALT-SILICON ALLOY

Magnesium

is

Ceramics

D.

compared

matrix

grain

composite

competing

MONOLITHIC

A 15X increase

strengths,

Mater.,

A model of damage on Weibull stastics

finite

effect Two

debonding,

OF LOW COST

TITANIUM

in yield

by

hardening

APPLICATIONS

base

strain

Constant and are considered.

substrate

University,

Metall.

relating the proportion of debonded W/ W boundaries to the volume fraction of W

coating

the

W

matrix. based

simulated

and

Hopkins

Acta

Vol 45, No 5, 1995, 1765-1774. A study of debonding at W/W

carbide forming layer between the emmisive thermodynamic

BOUNDARIES

described. The structure of the composite was a continuous network of W grains in

tubes, causes evolution of CO. This is attributed to reaction between MopC and

with

BY SHOT PEENING

It

MONOXIDE

RATES

M. Fodor, J.V. Wood Nottingham,

OF CARBON

EMISSION FROM OXIDE COATED MOLYBDENUM X-RAY ANODES

(In Rus-

of Fe-Si-Cl-H is used to

show that it is possible a chloride

PHASE

POWDERS MICROSTRUCTURE AND PROPERTIES OF MAGNESIUM-ALUMINIUMCALCIUM

ALLOYS

M.V. Susie A. lnoue et al. (Tohoku University, Sendai, Japan). J. Japan Sot. Powder Powder Vol

Metall., A. Kato et al. (Tohoku Japan).

Mater.

Science

A180, 1994. The production 20at%AlllO!%Ca pressure

Ar

University, Engng

Sendai,

A, A179/

of

atomization

amorphous powder and

by

Mghigh

subsequent

No

6,

1994,

705-708.

(In Japanese.) Production 15%Si

alloy

41,

process

powders

of amorphous by

with rapid

Cu roller ellipsoidal

a rotating cooling

is described. in shape

Tii20at%Coelectrode

on a spinning

The powders

with smooth

were

surfaces.

Sciences

et al.

and Arts,

Science

(Serbian

Academy

Belgrade,

Yugoslavia).

Vol 27, No 2, 1995,

of Sin&ring,

135-144. Effects of crystallization alloys,

of two Fe based

Fe-l4at%Si-8%B-5’%V-l’%Cu

13%Si-9%B-3%Nb-l.5%Cu, to

determine

parameters, magnetic

of

thermal electrical

and Fe-

was investigated and

kinetic

conductivity

and

permeability.

MPR April 1996 43