Effect of additions of rhenium or titanium and carbon on properties of molybdenum

Alloys

Inc.,

Elyfia,

Ohio,

USA)

Mute-rids

Processes, Vol 9, No 6, 1994,

and Mawuj 1087~1104. Production applications

of

Re

powder

are outlined.

and

Properties

its of Re

and Re alloys with MO and Ware

described.

Applications

structural

in nuclear

reactor

parts, in high temperature furnaces t,hermoelectric devices are discussed.

and

ADDITION

OF SINTERED

BRONZES

Warsaw,

additions and

Poland)

of

Prosz-

the

of Al bronze

are

presented.

of Al bronze

AlzO:l

with

additions

are

and discussed.

Hiraoka et al (Okayama

ht.

Ilniversity,

J. Rqfractory

strength

reported

Okaya-

Metals

&

of C and Re or Ti

and

MO were

ductility

of

investigated.

It is

thal Re and Ti increase

trans.granular

that

fracture

inter- and

strength

critical reduced.

stress. Critical temperature Further increases in strength

ductility

are given by additions

and is and

of C.

were found

MECHANICALLY DISPERSION

OF

HOT FORGING THROUGH

not of the

to be a 5.8 nm

to obey a parabolic

OF SINTERED

A PARTIALLY

DOWN CYLINDRICAL

ALLOYED

OXIDE

STRENGTHENED

Engineering

of sintered

at 1120’C

Cambridge,

(University IJK)

Metall.

of and

Trans. A. Vol 25A, No 4, 1994, 705.

714. Recrystallization stability of particles

behaviour, nature and and precipitation of y’

phase in a mechanically alloyed Ni base superalloy, MA760, were investigated. The alloy is shown to be recrystallized

with a sub-micron grain size. Secondary recrystallization occurs at 1215°C and there is a directional microstructure with precipitates of Y20:(/A120:( and Cr The Cr carbides redissolve on may re-precipitate. heating and Dissolution and precipitation of the y’ phase is also reported.

IMPURITY

horizontal

restraint

and

that

these merged in the later stages of densification. An empirical relationship between

density

retsraints to

and

the

is reported.

determine

ratio

of

flow

Fabrication

EFFECTS

during

to?

of grain

hot

effect

of

impurities

30, No

State

ht.

J.

2, 1994,

205-215. for

the

microeletronic

dissipation circuits

of

heat

are reviewed

with reference to materials selection and part fabrication. It is suggested that PM provides a means of making high quality parts with properties matched to the application. considered. include require

W-Cu and Al-Sic were Other materials suggested

AIN-Cu

and

novel processing

applications

Sic-Cu

which

techniques.

will Some

were outlined.

FABRICATION

OF COMPOSITIONALLY

GRADED TUNGSTEN-COPPER MATERIAL M.Takahashi

et al (Toshiba

in

and reduction

t,o

causing

of plasticity.

Experimental

and modelling

are described.

investigations

II. is shown that N, 0, P and

Si weaken the grain boundaries of W at ppm concentrations and that B and C enhance interatomic

interaction

boundaries.

across

grain

for

grain

Competition sites

between

is considered

distribution.

the

and enhance

different

to affect

B has the lowest

and may tend

to displace

impurity

free energy

other

elements

the duct,ility of W.

CHEMICALLY TUNGSTEN

alloys

THERMAL

Vol

Metalluqy,

in high

with respect

VAPOUR

DEPOSITED

AND TUNGSTEN-RHENIUM

et

APPLICATIONS

al

(Tokyo

*Japan)

Tungsten

Co,

Manu.

Pro-

Wcrterials

cesses, Vo:ol9, No 6, 1994, 1047~1060. The microstructures of CVD W and W-Re

PROCESSING

IJSA)

Vol 12, No 5,

boundaries

alloys is discussed

T.Hayashi

(Pennsylvania

Laboratory,

Int. J. Refiac-

251 I-260.

Toyama,

al

USA)

Metuls & Hard Materials,

Tungsten

et

ON ELECTRONIC

Maryland.

FOR STRUCTURAL

Pennsylvania,

6

is described.

(lJS Army Research

forging.

POWDER METALLURGY OF MATERIALS FOR

of

the

Pore flow was used

material

10 and

were

time

GLKrasko

boundary

fractional

for 300

times

dwell

Watertown,

elements

is always greater than the

alloy

STRUCTURE OF GRAIN BOUNDARIES AND COHESION OF TUNGSTEN

that to attain a given density the fractional

from H.K.Il.H.Bhadeshia

the W detached.

vertical

restraint

These

minutes. After this treatment the brazed sample was extensively cracked with bits of

the

It is shown

a

of

made by

between

cooling

with

Cohesion

Fe and 0.35%C

was studied.

Cu-Ag-Ti

Heating,

strength

College,

is described.

cycles

embrittlement

Powder

NICKEL

a

30 minutes

IRON

OPEN STEP

DIE CAVITY

(Regional

Materials

carbides.

does

7OO’C.

cycling

W/W-2O’%Cu,/W-

with a W/Cu couple

with

1993-1994,

University,

ALLOY

extruded

size

on

304L It is

rate law.

R.M.German CHARACTERIZATION

Mater.

layers

MANAGEMENT

Nickel

Cambridge,

Mater.

and thickness

MICROELECTRONIC

W.Sha,

oxide

particle

composition

formation

steel

Vol 12, No 5, 1993-1994,

The effects of additions recrystallized

und

surface of N atomized steel powders is described.

1993, 23-32. Hot forging

OF MOLYBDENUM

Hard Materials, 2611-268.

of Burgun-

Tiruchipalli, India) Powder Metallurgy Science and Technology, Vol 5, No 1,

EFFECT OF ADDITIONS OF RHENIUM OR TITANIZJM AND CARBON ON

ma, Japan).

of

and others

heating/cooling

Metall.

investigation

KSPandey

Molybdenum

PROPERTIES

brazing

of thermal

graded

are compared

ATOMIZED

(University

France)

3O%Cu;Cu

AND

outer layer of MnO/FezO:l over a 2.4 nm inner layer of CrzO:l, The kinetices of oxide

Technical

Metal.

Al,O:,

hardness

without

the

Dijon,

influence

et al. (Wojskowa

Results of the manufacture

on

dy,

G.Gasc

layers. The layer is shown

kow, Vol 27, No 1, 1994, 11-19. (In Polish).

compared

P.Brancconi,

reported

WITH

OF ALUMINA

J.Michalowski

and

REACTMTY OF NITROGEN 304L STAINLESS STEEL

An

MANUFACTURE

Density

CHARACTERIZATION

particle stainless

ALUMINIUM

with

SURFACE

An investigation compositionally

7%-ans. A, Vol 25A, No 3, 1994, 509-520.

Copper

Academy,

Iron and steel

Carp, Tokoha-

ma, Japan) Int. J. Refractory Metals & Hard Materials, Vol 12, No 5, 1993-1994, 243-250.

were

investigated

to

assess

suitability

as high temperature

materials. condition

The microstructure are reported to

deposition

conditions.

high hardnesses PLASMA

and surface depend on

Fine grain sizes and

are reported.

ACTIVATED

TUNGSTEN

their

structural

SINTERING

OF

POWDERS

G.Jones et al (University of California, Davis, California, I:SA) Materials and Processes, Vol 9, No 6, 1994, 1105-

Manuf

1114. Plasma activated and

high

process,

sintering,

temperature

is outlincad.

Three

are identified,

resistance

application

and

a short time

densification contributions

sintering, pressure

plasma

generation.

Densities of 80 to 92% were attained at 1775 to 2410°C for 2 to 8 minutes in air or vaccuum initial micrograin size being retained in W. The process was also used for net shape consolidation of WC-Co powders. It is suggested that densification may be enhanced without additives.

by surface

MPR March

activation

1995

37